Far infrared spectra of solid state aliphatic amino acids in different protonation states

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1 Far infrared speca of solid state aliphatic amino acids in different protonation states Aurélien Trivella 1, Thomas Gaillard 2,3, Roland H. Stote 2,4 Pea Hellwig 1, January 29, 2010 Supporting Information 1 Institut de Chimie, UMR 7177, Laboratoire de specoscopie vibrationnelle et élecochimie des biomolécules, Université de Sasbourg, 1 rue Blaise Pascal, F Sasbourg 2 Institut de Chimie, UMR 7177, Laboratoire de biophysicochimie moléculaire, Université de Sasbourg, 4 rue Blaise Pascal, F Sasbourg 3 Current address: Laboratoire de Biochimie (CNRS UMR7654), Department of Biology, Ecole Polytechnique, Palaiseau, France. 4 Current address: Biocomputing Group, Suctural Biology and Genomics Department, Institut de Génétique et de Biologie Moléculaire et Cellulaire, 1 rue Laurent Fries, BP 10142, Illkirch CEDEX, France. Corresponding author: hellwig@chimie.u-sasbg.fr both authors conibuted equally to this work 1

2 (a) Glycine beta (b) Glycine alpha (c) Glycine cation (d) Glycine anion Figure S1: Geomey of optimized suctures. Glycine β zwitterion (a), glycine α zwitterion (b), glycine cation (c), glycine anion (d). Ball and stick representation with hydrogen, carbon, niogen, oxygen, and other atoms in white, light blue, dark blue, red, and green, respectively. Molecules represented have their Cα atom inside the unit cell. Intermolecular polar contacts are indicated with an orange dashed line. Atom names for one molecule and unit cell axes are labelled. 2

3 (e) L-Alanine (f) L-Valine (g) L-Leucine (h) L-Isoleucine Figure S1: (continued) Geomey of optimized suctures. L-alanine (e), L-valine (f), L-leucine (g), L-isoleucine (h). Ball and stick representation with hydrogen, carbon, niogen, oxygen, and other atoms in white, light blue, dark blue, red, and green, respectively. Molecules represented have their Cα atom inside the unit cell. Intermolecular polar contacts are indicated with an orange dashed line. Atom names for one molecule and unit cell axes are labelled. 3

4 Table S1: Crystal system, space group, number of atoms per molecule, number of molecules per asymmeic unit, number of molecules per unit cell, number of normal modes, irreducible group representations, and symmey of acoustic modes. at./ mol./ mol./ acoustic modes molecule system group mol. asym. cell modes irreps x y z glycine β monoclinic P2 1 (4) A,B B B A glycine α monoclinic P2 1 /n (14) Ag,Bg,Au,Bu Bu Bu Au glycinium,cl monoclinic P2 1 /n (14) Ag,Bg,Au,Bu Bu Bu Au glycinate,na + orthorhombic P (19) A,B1,B2,B3 B1 B2 B3 L-alanine orthorhombic P (19) A,B1,B2,B3 B1 B2 B3 L-valine monoclinic P2 1 (4) A,B B B A L-leucine monoclinic P2 1 (4) A,B B B A L-isoleucine monoclinic P2 1 (4) A,B B B A 4

5 Table S2: Symmeized Pulay coordinates for glycine zwitterion number a coordinate b symbol c description 1 b N,Cα ν(ncα) NCα setch. 2 b Cα,C ν(cαc) CαC setch. 3 b C,O1 ν(co 2 ) CO 2 setch. 4 b C,O2 ν(co 2 ) CO 2 setch. 5 b Cα,Hα1 +b Cα,Hα2 ν s(cαh 2 ) CαH 2 sym. setch. 6 b Cα,Hα1 b Cα,Hα2 ν a(cαh 2 ) CαH 2 asym. setch. 7 b N,H1 ν(nh + 3 ) NH + 3 setch. 8 b N,H2 ν(nh + 3 ) NH + 3 setch. 9 b N,H3 ν(nh + 3 ) NH + 3 setch. 10 2a O1,C,O2 a Cα,C,O1 a Cα,C,O2 δ(co 2 ) CO 2 scissoring 11 a Cα,C,O1 a Cα,C,O2 ρ(co 2 ) CO 2 rocking 12 i O1,Cα,C,O2 ω(co 2 ) CO 2 wagging 13 5a Hα1,Cα,Hα2 a N,Cα,C δ(cαh 2 ) CαH 2 scissoring 14 5a N,Cα,C a Hα1,Cα,Hα2 δ(ncαc) NCαC scissoring 15 a Hα1,Cα,C a Hα2,Cα,C +a N,Cα,Hα1 a N,Cα,Hα2 ρ(cαh 2 ) CαH 2 rocking 16 a Hα1,Cα,C +a Hα2,Cα,C a N,Cα,Hα1 a N,Cα,Hα2 ω(cαh 2 ) CαH 2 wagging 17 a Hα1,Cα,C a Hα2,Cα,C a N,Cα,Hα1 +a N,Cα,Hα2 t(cαh 2 ) CαH 2 twisting 18 a H1,N,H2 +a H1,N,H3 +a H2,N,H3 δ s(nh + 3 ) NH + 3 sym. def. a H1,N,Cα a H2,N,Cα a H3,N,Cα 19 2a H2,N,H3 a H1,N,H2 a H1,N,H3 δ a(nh + 3 ) NH + 3 asym. def. 20 a H1,N,H2 a H1,N,H3 δ a(nh + 3 ) NH + 3 asym. def. 21 2a H1,N,Cα a H2,N,Cα a H3,N,Cα ρ(nh + 3 ) NH + 3 rocking 22 a H2,N,Cα a H3,N,Cα ρ(nh + 3 ) NH + 3 rocking 23 d x,n,cα,x τ(nh + 3 ) NH + 3 torsion 24 d x,cα,c,x τ(co 2 ) CO 2 torsion a arbiary numbering b b: bond, a: angle, d: dihedral, i: improper dihedral. Normalization factors are omitted and correspond to ( P c 2 i )1/2 c ν: setching, δ: bending, ρ: rocking, t: twisting, ω: wagging, τ: torsion 5

6 Table S3: Symmeized Pulay coordinates for glycine cation number a coordinate b symbol c description 1 b N,Cα ν(ncα) NCα setch. 2 b Cα,C ν(cαc) CαC setch. 3 b C,O1 ν(co 2 ) CO 2 setch. 4 b C,O2 ν(co 2 ) CO 2 setch. 5 b Cα,Hα1 +b Cα,Hα2 ν s(cαh 2 ) CαH 2 sym. setch. 6 b Cα,Hα1 b Cα,Hα2 ν a(cαh 2 ) CαH 2 asym. setch. 7 b N,H1 ν(nh + 3 ) NH + 3 setch. 8 b N,H2 ν(nh + 3 ) NH + 3 setch. 9 b N,H3 ν(nh + 3 ) NH + 3 setch. 10 2a O1,C,O2 a Cα,C,O1 a Cα,C,O2 δ(co 2 H) CO 2 H scissoring 11 a Cα,C,O1 a Cα,C,O2 ρ(co 2 H) CO 2 H rocking 12 i O1,Cα,C,O2 ω(co 2 H) CO 2 H wagging 13 5a Hα1,Cα,Hα2 a N,Cα,C δ(cαh 2 ) CαH 2 scissoring 14 5a N,Cα,C a Hα1,Cα,Hα2 δ(ncαc) NCαC scissoring 15 a Hα1,Cα,C a Hα2,Cα,C +a N,Cα,Hα1 a N,Cα,Hα2 ρ(cαh 2 ) CαH 2 rocking 16 a Hα1,Cα,C +a Hα2,Cα,C a N,Cα,Hα1 a N,Cα,Hα2 ω(cαh 2 ) CαH 2 wagging 17 a Hα1,Cα,C a Hα2,Cα,C a N,Cα,Hα1 +a N,Cα,Hα2 t(cαh 2 ) CαH 2 twisting 18 a H1,N,H2 +a H1,N,H3 +a H2,N,H3 δ s(nh + 3 ) NH + 3 sym. def. a H1,N,Cα a H2,N,Cα a H3,N,Cα 19 2a H2,N,H3 a H1,N,H2 a H1,N,H3 δ a(nh + 3 ) NH + 3 asym. def. 20 a H1,N,H2 a H1,N,H3 δ a(nh + 3 ) NH + 3 asym. def. 21 2a H1,N,Cα a H2,N,Cα a H3,N,Cα ρ(nh + 3 ) NH + 3 rocking 22 a H2,N,Cα a H3,N,Cα ρ(nh + 3 ) NH + 3 rocking 23 d x,n,cα,x τ(nh + 3 ) NH + 3 torsion 24 d x,cα,c,x τ(co 2 H) CO 2 H torsion 25 b O2,HO2 ν(oh) OH setch. 26 a C,O2,HO2 δ(coh) COH def. 27 d x,c,o2,x τ(co) CO torsion 28 b Cl,H1 +b Cl,H3 ν s(cl HN) Cl HN sym. setch. 29 b Cl,H1 b Cl,H3 ν a(cl HN) Cl HN asym. setch. 30 b Cl,HO2 ν(cl HO) Cl HO setch. a arbiary numbering b b: bond, a: angle, d: dihedral, i: improper dihedral. Normalization factors are omitted and correspond to ( P c 2 i )1/2 c ν: setching, δ: bending, ρ: rocking, t: twisting, ω: wagging, τ: torsion 6

7 Table S4: Symmeized Pulay coordinates for glycine anion number a coordinate b symbol c description 1 b N,Cα ν(ncα) NCα setch. 2 b Cα,C ν(cαc) CαC setch. 3 b C,O1 ν(co 2 ) CO 2 setch. 4 b C,O2 ν(co 2 ) CO 2 setch. 5 b Cα,Hα1 +b Cα,Hα2 ν s(cαh 2 ) CαH 2 sym. setch. 6 b Cα,Hα1 b Cα,Hα2 ν a(cαh 2 ) CαH 2 asym. setch. 7 b N,H1 ν(nh 2 ) NH 2 setch. 8 b N,H2 ν(nh 2 ) NH 2 setch. 9 2a O1,C,O2 a Cα,C,O1 a Cα,C,O2 δ(co 2 ) CO 2 scissoring 10 a Cα,C,O1 a Cα,C,O2 ρ(co 2 ) CO 2 rocking 11 i O1,Cα,C,O2 ω(co 2 ) CO 2 wagging 12 5a Hα1,Cα,Hα2 a N,Cα,C δ(cαh 2 ) CαH 2 scissoring 13 5a N,Cα,C a Hα1,Cα,Hα2 δ(ncαc) NCαC scissoring 14 a Hα1,Cα,C a Hα2,Cα,C +a N,Cα,Hα1 a N,Cα,Hα2 ρ(cαh 2 ) CαH 2 rocking 15 a Hα1,Cα,C +a Hα2,Cα,C a N,Cα,Hα1 a N,Cα,Hα2 ω(cαh 2 ) CαH 2 wagging 16 a Hα1,Cα,C a Hα2,Cα,C a N,Cα,Hα1 +a N,Cα,Hα2 t(cαh 2 ) CαH 2 twisting 17 2a H1,N,H2 a Cα,N,H1 a Cα,N,H2 δ(nh 2 ) NH 2 scissoring 18 a Cα,N,H1 a Cα,N,H2 ρ(nh 2 ) NH 2 rocking 19 i H1,Cα,N,H2 ω(nh 2 ) NH 2 wagging 20 d x,n,cα,x τ(nh 2 ) NH 2 torsion 21 d x,cα,c,x τ(co 2 ) CO 2 torsion 22 b O2,Na ν(ona + ) ONa + setch. 23 a C,O2,Na δ(cona + ) CONa + def. 24 d x,c,o2,x τ(cona + ) xcona + torsion a arbiary numbering b b: bond, a: angle, d: dihedral, i: improper dihedral. Normalization factors are omitted and correspond to ( P c 2 i )1/2 c ν: setching, δ: bending, ρ: rocking, t: twisting, ω: wagging, τ: torsion 7

8 Table S5: Symmeized Pulay coordinates for L-alanine zwitterion number a coordinate b symbol c description 1 b N,Cα ν(ncα) NCα setch. 2 b Cα,C ν(cαc) CαC setch. 3 b Cα,Cβ ν(cαcβ) CαCβ setch. 4 b C,O1 ν(co 2 ) CO 2 setch. 5 b C,O2 ν(co 2 ) CO 2 setch. 6 b Cα,Hα ν(cαh) CαH setch. 7 b N,H1 ν(nh + 3 ) NH + 3 setch. 8 b N,H2 ν(nh + 3 ) NH + 3 setch. 9 b N,H3 ν(nh + 3 ) NH + 3 setch. 10 b Cβ,Hβ1 +b Cβ,Hβ2 +b Cβ,Hβ3 ν s(cβh 3 ) CβH 3 sym. setch. 11 2b Cβ,Hβ1 b Cβ,Hβ2 b Cβ,Hβ3 ν a(cβh 3 ) CβH 3 asym. setch. 12 b Cβ,Hβ2 b Cβ,Hβ3 ν a(cβh 3 ) CβH 3 asym. setch. 13 2a O1,C,O2 a Cα,C,O1 a Cα,C,O2 δ(co 2 ) CO 2 scissoring 14 a Cα,C,O1 a Cα,C,O2 ρ(co 2 ) CO 2 rocking 15 i O1,Cα,C,O2 ω(co 2 ) CO 2 wagging 16 2a C,Cα,Hα a N,Cα,Hα a Cβ,Cα,Hα ρ(cαh) CαH rocking 17 a N,Cα,Hα a Cβ,Cα,Hα ρ(cαh) CαH rocking 18 4a C,Cα,N +a C,Cα,Cβ +a Cβ,Cα,N δ(ncαc) NCαC def. 19 4a C,Cα,Cβ +a Cβ,Cα,N +a C,Cα,N δ(ccαcβ) CCαCβ def. 20 4a Cβ,Cα,N +a C,Cα,N +a C,Cα,Cβ δ(ncαcβ) NCαCβ def. 21 a H1,N,H2 +a H1,N,H3 +a H2,N,H3 δ s(nh + 3 ) NH + 3 sym. def. a H1,N,Cα a H2,N,Cα a H3,N,Cα 22 2a H2,N,H3 a H1,N,H2 a H1,N,H3 δ a(nh + 3 ) NH + 3 asym. def. 23 a H1,N,H2 a H1,N,H3 δ a(nh + 3 ) NH + 3 asym. def. 24 2a H1,N,Cα a H2,N,Cα a H3,N,Cα ρ(nh + 3 ) NH + 3 rocking 25 a H2,N,Cα a H3,N,Cα ρ(nh + 3 ) NH + 3 rocking 26 a Hβ1,Cβ,Hβ2 +a Hβ1,Cβ,Hβ3 +a Hβ2,Cβ,Hβ3 δ s(cβh 3 ) CβH 3 sym. def. a Hβ1,Cβ,Cα a Hβ2,Cβ,Cα a Hβ3,Cβ,Cα 27 2a Hβ2,Cβ,Hβ3 a Hβ1,Cβ,Hβ2 a Hβ1,Cβ,Hβ3 δ a(cβh 3 ) CβH 3 asym. def. 28 a Hβ1,Cβ,Hβ2 a Hβ1,Cβ,Hβ3 δ a(cβh 3 ) CβH 3 asym. def. 29 2a Hβ3,Cβ,Cα a Hβ1,Cβ,Cα a Hβ2,Cβ,Cα ρ(cβh 3 ) CβH 3 rocking 30 a Hβ1,Cβ,Cα a Hβ2,Cβ,Cα ρ(cβh 3 ) CβH 3 rocking 31 d x,n,cα,x τ(nh + 3 ) NH + 3 torsion 32 d x,cα,c,x τ(co 2 ) CO 2 torsion 33 d x,cα,cβ,x τ(cβh 3 ) CβH 3 torsion a arbiary numbering b b: bond, a: angle, d: dihedral, i: improper dihedral. Normalization factors are omitted and correspond to ( P c 2 i )1/2 c ν: setching, δ: bending, ρ: rocking, t: twisting, ω: wagging, τ: torsion 8

9 Table S6: Symmeized Pulay coordinates for L-valine zwitterion number a coordinate b symbol c description 1 b N,Cα ν(ncα) NCα setch. 2 b Cα,C ν(cαc) CαC setch. 3 b Cα,Cβ ν(cαcβ) CαCβ setch. 4 b Cβ,Cγ1 ν(cβcγ) CβCγ setch. 5 b Cβ,Cγ2 ν(cβcγ) CβCγ setch. 6 b C,O1 ν(co 2 ) CO 2 setch. 7 b C,O2 ν(co 2 ) CO 2 setch. 8 b Cα,Hα ν(cαh) CαH setch. 9 b Cβ,Hβ ν(cβh) CβH setch. 10 b N,H1 ν(nh + 3 ) NH + 3 setch. 11 b N,H2 ν(nh + 3 ) NH + 3 setch. 12 b N,H3 ν(nh + 3 ) NH + 3 setch. 13 b Cγ1,Hγ11 +b Cγ1,Hγ12 +b Cγ1,Hγ13 ν s(cγh 3 ) CγH 3 sym. setch. 14 2b Cγ1,Hγ11 b Cγ1,Hγ12 b Cγ1,Hγ13 ν a(cγh 3 ) CγH 3 asym. setch. 15 b Cγ1,Hγ12 b Cγ1,Hγ13 ν a(cγh 3 ) CγH 3 asym. setch. 16 b Cγ2,Hγ21 +b Cγ2,Hγ22 +b Cγ2,Hγ23 ν s(cγh 3 ) CγH 3 sym. setch. 17 2b Cγ2,Hγ21 b Cγ2,Hγ22 b Cγ2,Hγ23 ν a(cγh 3 ) CγH 3 asym. setch. 18 b Cγ2,Hγ22 b Cγ2,Hγ23 ν a(cγh 3 ) CγH 3 asym. setch. 19 2a O1,C,O2 a Cα,C,O1 a Cα,C,O2 δ(co 2 ) CO 2 scissoring 20 a Cα,C,O1 a Cα,C,O2 ρ(co 2 ) CO 2 rocking 21 i O1,Cα,C,O2 ω(co 2 ) CO 2 wagging 22 2a C,Cα,Hα a N,Cα,Hα a Cβ,Cα,Hα ρ(cαh) CαH rocking 23 a N,Cα,Hα a Cβ,Cα,Hα ρ(cαh) CαH rocking 24 4a C,Cα,N +a C,Cα,Cβ +a Cβ,Cα,N δ(ncαc) NCαC def. 25 4a C,Cα,Cβ +a Cβ,Cα,N +a C,Cα,N δ(ccαcβ) CCαCβ def. 26 4a Cβ,Cα,N +a C,Cα,N +a C,Cα,Cβ δ(ncαcβ) NCαCβ def. 27 2a Cα,Cβ,Hβ a Cγ1,Cβ,Hβ a Cγ2,Cβ,Hβ ρ(cβh) CβH rocking 28 a Cγ1,Cβ,Hβ a Cγ2,Cβ,Hβ ρ(cβh) CβH rocking 29 4a Cγ1,Cβ,Cγ2 +a Cγ1,Cβ,Cα +a Cγ2,Cβ,Cα δ(cγcβcγ) CγCβCγ def. 30 4a Cγ1,Cβ,Cα +a Cγ2,Cβ,Cα +a Cγ1,Cβ,Cγ2 δ(cαcβcγ) CαCβCγ def. 31 4a Cγ2,Cβ,Cα +a Cγ1,Cβ,Cγ2 +a Cγ1,Cβ,Cα δ(cαcβcγ) CαCβCγ def. 32 a H1,N,H2 +a H1,N,H3 +a H2,N,H3 δ s(nh + 3 ) NH + 3 sym. def. a H1,N,Cα a H2,N,Cα a H3,N,Cα 33 2a H2,N,H3 a H1,N,H2 a H1,N,H3 δ a(nh + 3 ) NH + 3 asym. def. 34 a H1,N,H2 a H1,N,H3 δ a(nh + 3 ) NH + 3 asym. def. 35 2a H1,N,Cα a H2,N,Cα a H3,N,Cα ρ(nh + 3 ) NH + 3 rocking 36 a H2,N,Cα a H3,N,Cα ρ(nh + 3 ) NH + 3 rocking 37 a Hγ11,Cγ1,Hγ12 +a Hγ11,Cγ1,Hγ13 +a Hγ12,Cγ1,Hγ13 δ s(cγh 3 ) CγH 3 sym. def. a Hγ11,Cγ1,Cβ a Hγ12,Cγ1,Cβ a Hγ13,Cγ1,Cβ 38 2a Hγ12,Cγ1,Hγ13 a Hγ11,Cγ1,Hγ12 a Hγ11,Cγ1,Hγ13 δ a(cγh 3 ) CγH 3 asym. def. 39 a Hγ11,Cγ1,Hγ12 a Hγ11,Cγ1,Hγ13 δ a(cγh 3 ) CγH 3 asym. def. 40 2a Hγ11,Cγ1,Cβ a Hγ12,Cγ1,Cβ a Hγ13,Cγ1,Cβ ρ(cγh 3 ) CγH 3 rocking 41 a Hγ12,Cγ1,Cβ a Hγ13,Cγ1,Cβ ρ(cγh 3 ) CγH 3 rocking 42 a Hγ21,Cγ2,Hγ22 +a Hγ21,Cγ2,Hγ23 +a Hγ22,Cγ2,Hγ23 δ s(cγh 3 ) CγH 3 sym. def. a Hγ21,Cγ2,Cβ a Hγ22,Cγ2,Cβ a Hγ23,Cγ2,Cβ 43 2a Hγ22,Cγ2,Hγ23 a Hγ21,Cγ2,Hγ22 a Hγ21,Cγ2,Hγ23 δ a(cγh 3 ) CγH 3 asym. def. 44 a Hγ21,Cγ2,Hγ22 a Hγ21,Cγ2,Hγ23 δ a(cγh 3 ) CγH 3 asym. def. 45 2a Hγ21,Cγ2,Cβ a Hγ22,Cγ2,Cβ a Hγ23,Cγ2,Cβ ρ(cγh 3 ) CγH 3 rocking 46 a Hγ22,Cγ2,Cβ a Hγ23,Cγ2,Cβ ρ(cγh 3 ) CγH 3 rocking 47 d x,n,cα,x τ(nh + 3 ) NH + 3 torsion 48 d x,cα,c,x τ(co 2 ) CO 2 torsion 49 d x,cα,cβ,x τ(cαcβ) CαCβ torsion 50 d x,cβ,cγ1,x τ(cγh 3 ) CγH 3 torsion 51 d x,cβ,cγ2,x τ(cγh 3 ) CγH 3 torsion a arbiary numbering b b: bond, a: angle, d: dihedral, i: improper dihedral. Normalization factors are omitted and correspond to ( P c 2 i )1/2 c ν: setching, δ: bending, ρ: rocking, t: twisting, ω: wagging, τ: torsion 9

10 Table S7: Symmeized Pulay coordinates for L-leucine zwitterion number a coordinate b symbol c description 1 b N,Cα ν(ncα) NCα setch. 2 b Cα,C ν(cαc) CαC setch. 3 b Cα,Cβ ν(cαcβ) CαCβ setch. 4 b Cβ,Cγ ν(cβcγ) CβCγ setch. 5 b Cγ,Cδ1 ν(cγcδ) CγCδ setch. 6 b Cγ,Cδ2 ν(cγcδ) CγCδ setch. 7 b C,O1 ν(co 2 ) CO 2 setch. 8 b C,O2 ν(co 2 ) CO 2 setch. 9 b Cα,Hα ν(cαh) CαH setch. 10 b Cβ,Hβ1 +b Cβ,Hβ2 ν s(cβh 2 ) CβH 2 sym. setch. 11 b Cβ,Hβ1 b Cβ,Hβ2 ν a(cβh 2 ) CβH 2 asym. setch. 12 b Cγ,Hγ ν(cγh) CγH setch. 13 b N,H1 ν(nh + 3 ) NH + 3 setch. 14 b N,H2 ν(nh + 3 ) NH + 3 setch. 15 b N,H3 ν(nh + 3 ) NH + 3 setch. 16 b Cδ1,Hδ11 +b Cδ1,Hδ12 +b Cδ1,Hδ13 ν s(cδh 3 ) CδH 3 sym. setch. 17 2b Cδ1,Hδ11 b Cδ1,Hδ12 b Cδ1,Hδ13 ν a(cδh 3 ) CδH 3 asym. setch. 18 b Cδ1,Hδ12 b Cδ1,Hδ13 ν a(cδh 3 ) CδH 3 asym. setch. 19 b Cδ2,Hδ21 +b Cδ2,Hδ22 +b Cδ2,Hδ23 ν s(cδh 3 ) CδH 3 sym. setch. 20 2b Cδ2,Hδ21 b Cδ2,Hδ22 b Cδ2,Hδ23 ν a(cδh 3 ) CδH 3 asym. setch. 21 b Cδ2,Hδ22 b Cδ2,Hδ23 ν a(cδh 3 ) CδH 3 asym. setch. 22 2a O1,C,O2 a Cα,C,O1 a Cα,C,O2 δ(co 2 ) CO 2 scissoring 23 a Cα,C,O1 a Cα,C,O2 ρ(co 2 ) CO 2 rocking 24 i O1,Cα,C,O2 ω(co 2 ) CO 2 wagging 25 2a C,Cα,Hα a N,Cα,Hα a Cβ,Cα,Hα ρ(cαh) CαH rocking 26 a N,Cα,Hα a Cβ,Cα,Hα ρ(cαh) CαH rocking 27 4a C,Cα,N +a C,Cα,Cβ +a Cβ,Cα,N δ(ncαc) NCαC def. 28 4a C,Cα,Cβ +a Cβ,Cα,N +a C,Cα,N δ(ccαcβ) CCαCβ def. 29 4a Cβ,Cα,N +a C,Cα,N +a C,Cα,Cβ δ(ncαcβ) NCαCβ def. 30 5a Hβ1,Cβ,Hβ2 a Cα,Cβ,Cγ δ(cβh 2 ) CβH 2 scissoring 31 5a Cα,Cβ,Cγ a Hβ1,Cβ,Hβ2 δ(cαcβcγ) CαCβCγ scissoring 32 a Hβ1,Cβ,Cγ a Hβ2,Cβ,Cγ +a Cα,Cβ,Hβ1 a Cα,Cβ,Hβ2 ρ(cβh 2 ) CβH 2 rocking 33 a Hβ1,Cβ,Cγ +a Hβ2,Cβ,Cγ a Cα,Cβ,Hβ1 a Cα,Cβ,Hβ2 ω(cβh 2 ) CβH 2 wagging 34 a Hβ1,Cβ,Cγ a Hβ2,Cβ,Cγ a Cα,Cβ,Hβ1 +a Cα,Cβ,Hβ2 t(cβh 2 ) CβH 2 twisting 35 2a Cβ,Cγ,Hγ a Cδ1,Cγ,Hγ a Cδ2,Cγ,Hγ ρ(cγh) CγH rocking 36 a Cδ1,Cγ,Hγ a Cδ2,Cγ,Hγ ρ(cγh) CγH rocking 37 4a Cδ1,Cγ,Cδ2 +a Cδ1,Cγ,Cβ +a Cδ2,Cγ,Cβ δ(cδcγcδ) CδCγCδ def. 38 4a Cδ1,Cγ,Cβ +a Cδ2,Cγ,Cβ +a Cδ1,Cγ,Cδ2 δ(cβcγcδ) CβCγCδ def. 39 4a Cδ2,Cγ,Cβ +a Cδ1,Cγ,Cδ2 +a Cδ1,Cγ,Cβ δ(cβcγcδ) CβCγCδ def. 40 a H1,N,H2 +a H1,N,H3 +a H2,N,H3 δ s(nh + 3 ) NH + 3 sym. def. a H1,N,Cα a H2,N,Cα a H3,N,Cα 41 2a H2,N,H3 a H1,N,H2 a H1,N,H3 δ a(nh + 3 ) NH + 3 asym. def. 42 a H1,N,H2 a H1,N,H3 δ a(nh + 3 ) NH + 3 asym. def. 43 2a H1,N,Cα a H2,N,Cα a H3,N,Cα ρ(nh + 3 ) NH + 3 rocking 44 a H2,N,Cα a H3,N,Cα ρ(nh + 3 ) NH + 3 rocking 45 a Hδ11,Cδ1,Hδ12 +a Hδ11,Cδ1,Hδ13 +a Hδ12,Cδ1,Hδ13 δ s(cδh 3 ) CδH 3 sym. def. a Hδ11,Cδ1,Cγ a Hδ12,Cδ1,Cγ a Hδ13,Cδ1,Cγ 46 2a Hδ12,Cδ1,Hδ13 a Hδ11,Cδ1,Hδ12 a Hδ11,Cδ1,Hδ13 δ a(cδh 3 ) CδH 3 asym. def. 47 a Hδ11,Cδ1,Hδ12 a Hδ11,Cδ1,Hδ13 δ a(cδh 3 ) CδH 3 asym. def. 48 2a Hδ11,Cδ1,Cγ a Hδ12,Cδ1,Cγ a Hδ13,Cδ1,Cγ ρ(cδh 3 ) CδH 3 rocking 49 a Hδ12,Cδ1,Cγ a Hδ13,Cδ1,Cγ ρ(cδh 3 ) CδH 3 rocking 50 a Hδ21,Cδ2,Hδ22 +a Hδ21,Cδ2,Hδ23 +a Hδ22,Cδ2,Hδ23 δ s(cδh 3 ) CδH 3 sym. def. a Hδ21,Cδ2,Cγ a Hδ22,Cδ2,Cγ a Hδ23,Cδ2,Cγ 51 2a Hδ22,Cδ2,Hδ23 a Hδ21,Cδ2,Hδ22 a Hδ21,Cδ2,Hδ23 δ a(cδh 3 ) CδH 3 asym. def. 52 a Hδ21,Cδ2,Hδ22 a Hδ21,Cδ2,Hδ23 δ a(cδh 3 ) CδH 3 asym. def. 53 2a Hδ21,Cδ2,Cγ a Hδ22,Cδ2,Cγ a Hδ23,Cδ2,Cγ ρ(cδh 3 ) CδH 3 rocking 54 a Hδ22,Cδ2,Cγ a Hδ23,Cδ2,Cγ ρ(cδh 3 ) CδH 3 rocking 55 d x,n,cα,x τ(nh + 3 ) NH + 3 torsion 56 d x,cα,c,x τ(co 2 ) CO 2 torsion 57 d x,cα,cβ,x τ(cαcβ) CαCβ torsion 58 d x,cβ,cγ,x τ(cβcγ) CβCγ torsion 59 d x,cγ,cδ1,x τ(cδh 3 ) CδH 3 torsion 60 d x,cγ,cδ2,x τ(cδh 3 ) CδH 3 torsion a arbiary numbering b b: bond, a: angle, d: dihedral, i: improper dihedral. Normalization factors are omitted and correspond to ( P c 2 i )1/2 c ν: setching, δ: bending, ρ: rocking, t: twisting, ω: wagging, τ: torsion 10

11 Table S8: Symmeized Pulay coordinates for L-isoleucine zwitterion number a coordinate b symbol c description 1 b N,Cα ν(ncα) NCα setch. 2 b Cα,C ν(cαc) CαC setch. 3 b Cα,Cβ ν(cαcβ) CαCβ setch. 4 b Cβ,Cγ1 ν(cβcγ1) CβCγ1 setch. 5 b Cβ,Cγ2 ν(cβcγ2) CβCγ2 setch. 6 b Cγ1,Cδ ν(cγ1cδ) Cγ1Cδ setch. 7 b C,O1 ν(co 2 ) CO 2 setch. 8 b C,O2 ν(co 2 ) CO 2 setch. 9 b Cα,Hα ν(cαh) CαH setch. 10 b Cβ,Hβ ν(cβh) CβH setch. 11 b Cγ1,Hγ11 +b Cγ1,Hγ12 ν s(cγh 2 ) Cγ1H 2 asym. setch. 12 b Cγ1,Hγ11 b Cγ1,Hγ12 ν a(cγh 2 ) Cγ1H 2 sym. setch. 13 b N,H1 ν(nh + 3 ) NH + 3 setch. 14 b N,H2 ν(nh + 3 ) NH + 3 setch. 15 b N,H3 ν(nh + 3 ) NH + 3 setch. 16 b Cγ2,Hγ21 +b Cγ2,Hγ22 +b Cγ2,Hγ23 ν s(cγh 3 ) Cγ2H 3 sym. setch. 17 2b Cγ2,Hγ21 b Cγ2,Hγ22 b Cγ2,Hγ23 ν a(cγh 3 ) Cγ2H 3 asym. setch. 18 b Cγ2,Hγ22 b Cγ2,Hγ23 ν a(cγh 3 ) Cγ2H 3 asym. setch. 19 b Cδ,Hδ1 +b Cδ,Hδ2 +b Cδ,Hδ3 ν s(cδh 3 ) CδH 3 sym. setch. 20 2b Cδ,Hδ1 b Cδ,Hδ2 b Cδ,Hδ3 ν a(cδh 3 ) CδH 3 asym. setch. 21 b Cδ,Hδ2 b Cδ,Hδ3 ν a(cδh 3 ) CδH 3 asym. setch. 22 2a O1,C,O2 a Cα,C,O1 a Cα,C,O2 δ(co 2 ) CO 2 scissoring 23 a Cα,C,O1 a Cα,C,O2 ρ(co 2 ) CO 2 rocking 24 i O1,Cα,C,O2 ω(co 2 ) CO 2 wagging 25 2a C,Cα,Hα a N,Cα,Hα a Cβ,Cα,Hα ρ(cαh) CαH rocking 26 a N,Cα,Hα a Cβ,Cα,Hα ρ(cαh) CαH rocking 27 4a C,Cα,N +a C,Cα,Cβ +a Cβ,Cα,N δ(ncαc) NCαC def. 28 4a C,Cα,Cβ +a Cβ,Cα,N +a C,Cα,N δ(ccαcβ) CCαCβ def. 29 4a Cβ,Cα,N +a C,Cα,N +a C,Cα,Cβ δ(ncαcβ) NCαCβ def. 30 2a Cα,Cβ,Hβ a Cγ1,Cβ,Hβ a Cγ2,Cβ,Hβ ρ(cβh) CβH rocking 31 a Cγ1,Cβ,Hβ a Cγ2,Cβ,Hβ ρ(cβh) CβH rocking 32 4a Cγ1,Cβ,Cγ2 +a Cγ1,Cβ,Cα +a Cγ2,Cβ,Cα δ(cγcβcγ) Cγ1CβCγ2 def. 33 4a Cγ1,Cβ,Cα +a Cγ2,Cβ,Cα +a Cγ1,Cβ,Cγ2 δ(cαcβcγ1) CαCβCγ1 def. 34 4a Cγ2,Cβ,Cα +a Cγ1,Cβ,Cγ2 +a Cγ1,Cβ,Cα δ(cαcβcγ2) CαCβCγ2 def. 35 5a Hγ11,Cγ1,Hγ12 a Cβ,Cγ1,Cδ δ(cγ1h 2 ) Cγ1H 2 scissoring 36 5a Cβ,Cγ1,Cδ a Hγ11,Cγ1,Hγ12 δ(cβcγ1cδ) CβCγ1Cδ scissoring 37 a Hγ11,Cγ1,Cδ a Hγ12,Cγ1,Cδ +a Cβ,Cγ1,Hγ11 a Cβ,Cγ1,Hγ12 ρ(cγ1h 2 ) Cγ1H 2 rocking 38 a Hγ11,Cγ1,Cδ +a Hγ12,Cγ1,Cδ a Cβ,Cγ1,Hγ11 a Cβ,Cγ1,Hγ12 ω(cγ1h 2 ) Cγ1H 2 wagging 39 a Hγ11,Cγ1,Cδ a Hγ12,Cγ1,Cδ a Cβ,Cγ1,Hγ11 +a Cβ,Cγ1,Hγ12 t(cγ1h 2 ) Cγ1H 2 twisting 40 a H1,N,H2 +a H1,N,H3 +a H2,N,H3 δ s(nh + 3 ) NH + 3 sym. def. a H1,N,Cα a H2,N,Cα a H3,N,Cα 41 2a H2,N,H3 a H1,N,H2 a H1,N,H3 δ a(nh + 3 ) NH + 3 asym. def. 42 a H1,N,H2 a H1,N,H3 δ a(nh + 3 ) NH + 3 asym. def. 43 2a H1,N,Cα a H2,N,Cα a H3,N,Cα ρ(nh + 3 ) NH + 3 rocking 44 a H2,N,Cα a H3,N,Cα ρ(nh + 3 ) NH + 3 rocking 45 a Hγ21,Cγ2,Hγ22 +a Hγ21,Cγ2,Hγ23 +a Hγ22,Cγ2,Hγ23 δ s(cγh 3 ) Cγ2H 3 sym. def. a Hγ21,Cγ2,Cβ a Hγ22,Cγ2,Cβ a Hγ23,Cγ2,Cβ 46 2a Hγ22,Cγ2,Hγ23 a Hγ21,Cγ2,Hγ22 a Hγ21,Cγ2,Hγ23 δ a(cγh 3 ) Cγ2H 3 asym. def. 47 a Hγ21,Cγ2,Hγ22 a Hγ21,Cγ2,Hγ23 δ a(cγh 3 ) Cγ2H 3 asym. def. 48 2a Hγ21,Cγ2,Cβ a Hγ22,Cγ2,Cβ a Hγ23,Cγ2,Cβ ρ(cγh 3 ) Cγ2H 3 rocking 49 a Hγ22,Cγ2,Cβ a Hγ23,Cγ2,Cβ ρ(cγh 3 ) Cγ2H 3 rocking 50 a Hδ1,Cδ,Hδ2 +a Hδ1,Cδ,Hδ3 +a Hδ2,Cδ,Hδ3 δ s(cδh 3 ) CδH 3 sym. def. a Hδ1,Cδ,Cγ1 a Hδ2,Cδ,Cγ1 a Hδ3,Cδ,Cγ1 51 2a Hδ2,Cδ,Hδ3 a Hδ1,Cδ,Hδ2 a Hδ1,Cδ,Hδ3 δ a(cδh 3 ) CδH 3 asym. def. 52 a Hδ1,Cδ,Hδ2 a Hδ1,Cδ,Hδ3 δ a(cδh 3 ) CδH 3 asym. def. 53 2a Hδ1,Cδ,Cγ1 a Hδ2,Cδ,Cγ1 a Hδ3,Cδ,Cγ1 ρ(cδh 3 ) CδH 3 rocking 54 a Hδ2,Cδ,Cγ1 a Hδ3,Cδ,Cγ1 ρ(cδh 3 ) CδH 3 rocking 55 d x,n,cα,x τ(nh + 3 ) NH + 3 torsion 56 d x,cα,c,x τ(co 2 ) CO 2 torsion 57 d x,cα,cβ,x τ(cαcβ) CαCβ torsion 58 d x,cβ,cγ1,x τ(cβcγ1) CβCγ1 torsion 59 d x,cβ,cγ2,x τ(cγ2h 3 ) Cγ2H 3 torsion 60 d x,cγ1,cδ,x τ(cδh 3 ) CδH 3 torsion a arbiary numbering b b: bond, a: angle, d: dihedral, i: improper dihedral. Normalization factors are omitted and correspond to ( P c 2 i )1/2 c ν: setching, δ: bending, ρ: rocking, t: twisting, ω: wagging, τ: torsion 11

12 Table S9: Calculated frequencies, infrared intensities, irreducible group representation, and potential energy disibutions for β glycine zwitterion. number freq. IR int. irrep. P.E.D. (greater than 10%) (cm 1 ) ((D/Å) 2 /u) A 40δ(CO 2 ),18ω(CO 2 ),16δ(NCαC) B 38δ(CO 2 ),18ω(CO 2 ),16δ(NCαC) A 80τ(NH + 3 ) B 80τ(NH + 3 ),12ω(CO 2 ) A 30ω(CO 2 ),18δ(CO 2 ),14ν(CαC),14ρ(CαH 2 ),12τ(NH + 3 ) B 28ω(CO 2 ),18δ(CO 2 ),14ν(CαC),14ρ(CαH 2 ),14τ(NH + 3 ) A 44ρ(CO 2 ),18δ(NCαC) B 42ρ(CO 2 ),18δ(NCαC) A 56δ(NCαC),34ρ(CO 2 ) B 58δ(NCαC),34ρ(CO 2 ) B 72rot,20τ(CO 2 ) A 78rot,16τ(CO 2 ) B 70rot, A 82rot A 74τ(CO 2 ),16rot B 50rot, B 42,40rot A 46rot, A B 50,34τ(CO 2 ) A 70,20rot B A B 50,30rot,22τ(CO 2 ) 12

13 Table S10: Calculated frequencies, infrared intensities, irreducible group representation, and potential energy disibutions for α glycine zwitterion. number freq. IR int. irrep. P.E.D. (greater than 10%) (cm 1 ) ((D/Å) 2 /u) Ag 36δ(CO 2 ),24ω(CO 2 ),16δ(NCαC) Bg 36δ(CO 2 ),24ω(CO 2 ),16δ(NCαC) Bu 36δ(CO 2 ),20ω(CO 2 ),20δ(NCαC) Au 36δ(CO 2 ),20ω(CO 2 ),16δ(NCαC) Au 88τ(NH + 3 ) Bu 88τ(NH + 3 ) Bg 80τ(NH + 3 ) Ag 84τ(NH + 3 ) Ag 28ω(CO 2 ),24δ(CO 2 ),16ν(CαC) Bg 28ω(CO 2 ),20δ(CO 2 ),16ν(CαC) Bu 32ω(CO 2 ),24δ(CO 2 ),20ν(CαC),12ρ(CαH 2 ) Au 36ω(CO 2 ),24δ(CO 2 ),20ν(CαC),12ρ(CαH 2 ) Bu 40ρ(CO 2 ),16δ(NCαC) Au 40ρ(CO 2 ),20δ(NCαC) Ag 48ρ(CO 2 ),12δ(NCαC) Bg 48ρ(CO 2 ),16δ(NCαC) Bg 64δ(NCαC),28ρ(CO 2 ) Ag 64δ(NCαC),28ρ(CO 2 ) Bu 60δ(NCαC),36ρ(CO 2 ) Au 60δ(NCαC),36ρ(CO 2 ) Bu 92rot Au 72rot,16τ(CO 2 ) Bu 76rot,16τ(CO 2 ) Ag 68rot Bg 84rot Au 92rot Bg 72rot Ag 56rot,28τ(CO 2 ) Bg 40τ(CO 2 ),20,20rot Bu 56τ(CO 2 ),32rot Ag 36,32rot,16τ(CO 2 ) Au 60τ(CO 2 ),12rot Ag 40rot,20,12τ(CO 2 ) Bg 52rot, Au 64rot,24τ(CO 2 ) Bu 64rot,28τ(CO 2 ) Bg 64,24τ(CO 2 ) Ag 52,24τ(CO 2 ),24rot Bg 76,16τ(CO 2 ) Ag Bu Au Au Bg 76,12rot Ag 72,16rot Au Bu Bu

14 Table S11: Calculated frequencies, infrared intensities, irreducible group representation, and potential energy disibutions for glycine cation. number freq. IR int. irrep. P.E.D. (greater than 10%) (cm 1 ) ((D/Å) 2 /u) Au 48δ(CO 2 H),24δ(NCαC) Ag 48δ(CO 2 H),24δ(NCαC) Bu 48δ(CO 2 H),20δ(NCαC) Bg 48δ(CO 2 H),20δ(NCαC) Bg 64ω(CO 2 H),24ρ(CαH 2 ) Bu 64ω(CO 2 H),24ρ(CαH 2 ) Ag 68ω(CO 2 H),28ρ(CαH 2 ) Au 68ω(CO 2 H),28ρ(CαH 2 ) Ag 40ρ(CO 2 H),20δ(CO 2 H) Au 40ρ(CO 2 H),24δ(CO 2 H) Bg 40ρ(CO 2 H),20δ(CO 2 H),12δ(NCαC) Bu 40ρ(CO 2 H),20δ(CO 2 H),12δ(NCαC) Ag 56τ(NH + 3 ),40ν a(cl HN) Au 56τ(NH + 3 ),40ν a(cl HN) Bg 92ν a(cl HN) Bu 92ν a(cl HN) Bg 60δ(NCαC),36ρ(CO 2 H) Bu 60δ(NCαC),36ρ(CO 2 H) Ag 52δ(NCαC),32ρ(CO 2 H) Au 52δ(NCαC),32ρ(CO 2 H) Bg 40ν s(cl HN),32τ(CO 2 H),16rot Bu 40ν s(cl HN),36τ(CO 2 H) Ag 68ν s(cl HN),44ν a(cl HN) Au 52ν s(cl HN),44ν a(cl HN),16rot Bg 44ν s(cl HN),40rot,32τ(NH + 3 ) Bu 44ν s(cl HN),40τ(NH + 3 ),36rot Ag 32τ(CO 2 H),24rot Au 28ν s(cl HN),28τ(CO 2 H),20rot Bg 52rot,32ν(Cl HO) Bu 52rot,36ν(Cl HO) Ag 36ν(Cl HO),28τ(CO 2 H),24rot, Au 36ν(Cl HO),24rot,24τ(CO 2 H), Au 76rot Ag 72rot,20ν a(cl HN) Bg 60τ(CO 2 H),12rot Ag 32τ(NH + 3 ),24τ(CO 2 H),16rot Bu 52τ(CO 2 H),36τ(NH + 3 ) Au 48τ(NH + 3 ),20ν a(cl HN),20τ(CO 2 H) Bg 36τ(NH + 3 ),28rot,20ν a(cl HN) Bu 28rot,20ν a(cl HN),12τ(CO 2 H) Ag 52,20τ(NH + 3 ),16rot Bg 52ν(Cl HO),24τ(NH + 3 ) Au 44ν(Cl HO),20τ(CO 2 H),16rot Ag 48ν(Cl HO),16τ(CO 2 H) Bu 48ν(Cl HO),20rot Bg 48rot, Au 88rot Ag 48rot, Au 68,12τ(NH + 3 ) Bu 72rot Bg 44,36rot Bu Ag Bg Au Bg Ag Au Bu Bu 88 14

15 Table S12: Calculated frequencies, infrared intensities, irreducible group representation, and potential energy disibutions for glycine anion. number freq. IR int. irrep. P.E.D. (greater than 10%) (cm 1 ) ((D/Å) 2 /u) B2 40δ(CO 2 ),16ν(CαC),16δ(NCαC),12ρ(CO 2 ) B1 32δ(CO 2 ),16ν(CαC),16ρ(CO 2 ),12δ(NCαC) B3 44δ(CO 2 ),20δ(NCαC),16ν(CαC),12ρ(CO 2 ) A 36δ(CO 2 ),16ρ(CO 2 ),16ν(CαC),16δ(NCαC) B1 56ω(CO 2 ),24ρ(CαH 2 ) A 52ω(CO 2 ),24ρ(CαH 2 ) B2 44ω(CO 2 ),20ρ(CαH 2 ) B3 48ω(CO 2 ),20ρ(CαH 2 ) B1 52ν(ONa + ),12ρ(CO 2 ) A 44ν(ONa + ),16ρ(CO 2 ) B2 52ν(ONa + ),12ρ(CO 2 ) B3 56ν(ONa + ),12ρ(CO 2 ) B2 40rot,28,24δ(CONa + ) B3 36rot,28,24δ(CONa + ) A 40rot,24δ(CONa + ), B1 40rot,16δ(CONa + ), B2 20rot,16ν(ONa + ) B1 16ν(ONa + ),16δ(NCαC),12δ(CONa + ),12rot B3 16δ(CONa + ),12ρ(CO 2 ),12ν(ONa + ) A 24ν(ONa + ),16,12δ(CONa + ),12δ(NCαC) B3 44rot,16ν(ONa + ),16τ(CONa + ) A 52rot,20τ(CONa + ), B1 24τ(CONa + ),24rot, B2 20τ(CONa + ),20rot,16ρ(CO 2 ), B3 92τ(NH 2 ) B1 92τ(NH 2 ) A 96τ(NH 2 ) B2 92τ(NH 2 ) B2 56δ(NCαC),24ρ(CO 2 ) A 52δ(NCαC),28ρ(CO 2 ),12δ(CONa + ) B1 52δ(NCαC),28ρ(CO 2 ) B3 60δ(NCαC),28ρ(CO 2 ) B3 44δ(CONa + ), B1 28rot,24,16τ(CO 2 ) B2 32τ(CO 2 ),28rot,16τ(CONa + ) B2 28δ(CONa + ),20,20rot B3 40τ(CO 2 ),40rot A 32,16rot,12δ(CONa + ) A 36τ(CO 2 ),28rot B1 36τ(CONa + ),16τ(CO 2 ),12rot B1 28δ(CONa + ),20τ(CO 2 ),12rot B3 52τ(CONa + ) A 44τ(CONa + ),16τ(CO 2 ) B2 36τ(CONa + ),16δ(CONa + ),16rot B A 32rot, B1 40rot, A 68,16τ(CONa + ) B3 32,20rot,16τ(CO 2 ) B1 48,20τ(CONa + ) B2 52τ(CO 2 ),32rot, B1 48τ(CO 2 ),28rot, A 44τ(CO 2 ),28rot, B3 36rot,24,24τ(CO 2 ) B2 36rot, B3 44rot,40,12τ(CO 2 ) A 44,36rot B3 56,20rot B B1 44,32rot 15

16 Table S13: Calculated frequencies, infrared intensities, irreducible group representation, and potential energy disibutions for L-alanine zwitterion. number freq. IR int. irrep. P.E.D. (greater than 10%) (cm 1 ) ((D/Å) 2 /u) B1 68ω(CO 2 ) A 64ω(CO 2 ) B3 64ω(CO 2 ) B2 64ω(CO 2 ) A 28δ(CO 2 ),24δ(NCαC),12ν(CαC) B1 28δ(CO 2 ),24δ(NCαC),12ν(CαC) B3 28δ(CO 2 ),24δ(NCαC) B2 28δ(CO 2 ),24δ(NCαC),12ρ(CO 2 ) B2 76τ(NH + 3 ) B1 84τ(NH + 3 ) B3 76τ(NH + 3 ) A 80τ(NH + 3 ) B2 28ρ(CO 2 ),16ν(CαC) B3 28ρ(CO 2 ),12ν(CαC) B1 28ρ(CO 2 ),16ν(CαC),16δ(CO 2 ) A 24ρ(CO 2 ),16ν(CαC),16δ(CO 2 ) B3 72δ(NCαCβ) B2 76δ(NCαCβ) B1 72δ(NCαCβ) A 72δ(NCαCβ) B1 36δ(NCαC),28ρ(CO 2 ) B2 28ρ(CO 2 ),28δ(NCαC),16τ(CβH 3 ),16δ(CCαCβ) A 28ρ(CO 2 ),28δ(NCαC),20τ(CβH 3 ) B3 28ρ(CO 2 ),24δ(NCαC),24τ(CβH 3 ),16δ(CCαCβ) B1 64δ(CCαCβ),12ω(CO 2 ) A 52δ(CCαCβ),16δ(NCαC),12ρ(CO 2 ) B2 60δ(CCαCβ),12ω(CO 2 ),12δ(NCαC) B3 40δ(CCαCβ),32τ(CβH 3 ) A 76τ(CβH 3 ) B3 32τ(CβH 3 ),24δ(NCαC),20ρ(CO 2 ),12δ(CCαCβ) B2 64τ(CβH 3 ) B1 60τ(CβH 3 ) B3 72rot B1 32τ(CO 2 ),32rot,24τ(CβH 3 ) B2 44rot,20τ(CO 2 ),20τ(CβH 3 ) A 48rot, B3 40,28rot,16τ(CO 2 ) B1 72rot A 64rot,28τ(CO 2 ) B2 72rot,20τ(CO 2 ) B2 60rot,36τ(CO 2 ) B3 48rot,20τ(CO 2 ) A 48rot,40τ(CO 2 ) B1 60rot, B3 60,12rot B B1 32,28τ(CO 2 ),20rot A 40,40rot B3 44τ(CO 2 ),24rot, B2 52rot,28,12τ(CO 2 ) A B A 40rot, B3 56,24rot B B1 52rot, A B B3 64,20rot B

17 Table S14: Calculated frequencies, infrared intensities, irreducible group representation, and potential energy disibutions for L-valine zwitterion. number freq. IR int. irrep. P.E.D. (greater than 10%) (cm 1 ) ((D/Å) 2 /u) A 32δ(CO 2 ),16ω(CO2 ),16ν(CαCβ) B 34δ(CO 2 ),16ω(CO2 ),16ν(CαCβ) B 48ω(CO 2 ),18ν(CαCβ) A 48ω(CO 2 ),18ν(CαCβ) B 46δ(CO 2 ),16δ(NCαC) A 44δ(CO 2 ),16δ(NCαC) B 18δ(NCαC),16δ(CO 2 ),16ω(CO2 ),12ρ(CO2 ) A 18δ(NCαC),16δ(CO 2 ),16ω(CO2 ),14ρ(CO2 ) B + 86τ(NH 3 ) A + 88τ(NH 3 ) A + 80τ(NH 3 ) B + 74τ(NH 3 ) B 16ρ(CO 2 ),12ν(NCα),12δ(NCαCβ) A 24ρ(CO 2 ),14ν(NCα),12δ(NCαCβ) A 16ρ(CO 2 ),16ν(CαC),16ν(NCα),12δ(CO2 ) B 18ρ(CO 2 ),14ν(CαC) A 36δ(CαCβCγ),14ν(CαC),14δ(CγCβCγ) B 36δ(CαCβCγ),14ν(CαC),14δ(CγCβCγ) B 28δ(NCαCβ),16ρ(CO 2 ),12δ(CγCβCγ) A 28δ(NCαCβ),20ρ(CO 2 ),16δ(CγCβCγ) B 26δ(NCαCβ),18δ(CαCβCγ),12ρ(CO 2 ) A 26δ(NCαCβ),16δ(CαCβCγ),12ρ(CO 2 ),12δ(CγCβCγ) B 42δ(CγCβCγ),14δ(NCαCβ) A 40δ(CγCβCγ),16δ(NCαCβ),12ν(CαC) B 50δ(CαCβCγ),16δ(CγCβCγ) A 54δ(CαCβCγ),14δ(CγCβCγ) B 44δ(CγCβCγ),14δ(NCαC) A 50δ(CγCβCγ),22δ(CαCβCγ) B 38ρ(CO 2 ),24δ(NCαC),18δ(CαCβCγ) A 42δ(NCαC),38ρ(CO 2 ) B 50δ(CαCβCγ) A 46δ(CαCβCγ),12δ(NCαC) A 28δ(NCαC),26ρ(CO 2 ) B 24ρ(CO 2 ),24δ(NCαC) B 24δ(CCαCβ),20τ(CO 2 ) A 24δ(CCαCβ),16τ(CO 2 ),12rot A 62τ(CγH 3 ) B 60τ(CγH 3 ) B 32δ(CαCβCγ),14δ(CCαCβ),14δ(NCαCβ) B 26τ(CO 2 ),18τ(CγH3 ),12δ(CαCβCγ) A 22δ(CαCβCγ),22δ(CCαCβ) A 26τ(CγH 3 ),22δ(CαCβCγ),22δ(NCαCβ),14τ(CO 2 ) B 54τ(CγH 3 ) A 72τ(CγH 3 ) B 18τ(CγH 3 ),16rot,12τ(CαCβ) A 28τ(CO 2 ),20τ(CγH3 ),14δ(CCαCβ) B 82τ(CγH 3 ) A 62τ(CγH 3 ) B 40τ(CO 2 ),16rot,14δ(CCαCβ) A 28τ(CαCβ),26rot,22τ(CγH 3 ) B 38τ(CγH 3 ),12τ(CαCβ) A 22τ(CO 2 ),12τ(CγH3 ),12δ(CCαCβ) B 36τ(CO 2 ),18δ(CCαCβ) A 58τ(CγH 3 ),18rot B 40τ(CγH 3 ),22rot,12τ(CO 2 ) A 24τ(CO 2 ),20rot,12τ(CαCβ) B 44rot,40τ(CαCβ) A 24rot,24τ(CαCβ), B 30rot,28τ(CαCβ), A 38rot,34τ(CαCβ) A 46,30rot B 34rot,32,14τ(CαCβ) A 48rot B 38rot, A 32,30rot B 36,30rot A 68,14rot B 44rot, A 40,26rot,16τ(CαCβ) B 40τ(CαCβ),24rot, A 34rot,18,16τ(CαCβ) B 50,26rot A 38,28rot B 62,12rot A 46,24rot B 62,14rot B 54,18rot A 62,18rot A 44,36rot B 44,38rot 17

18 Table S15: Calculated frequencies, infrared intensities, irreducible group representation, and potential energy disibutions for L-leucine zwitterion. number freq. IR int. irrep. P.E.D. (greater than 10%) (cm 1 ) ((D/Å) 2 /u) B 66ω(CO 2 ) A 62ω(CO 2 ) A 66ω(CO 2 ) B 64ω(CO 2 ) B 26δ(CO 2 ),18δ(NCαC),14ρ(CO2 ) A 24δ(CO 2 ),16δ(NCαC),12ρ(CO2 ) B 26δ(CO 2 ),20δ(NCαC),12ρ(CO2 ) A 24δ(CO 2 ),18δ(NCαC),12ρ(CO2 ) A + 94τ(NH 3 ) B + 86τ(NH 3 ) A + 88τ(NH 3 ) B + 86τ(NH 3 ) A 18ρ(CO 2 ),12δ(NCαCβ) B 14ρ(CO 2 ),14δ(NCαCβ) B 16ρ(CO 2 ),12ν(CαC) A 20ρ(CO 2 ) A 34δ(CδCγCδ),12δ(CβCγCδ) B 34δ(CδCγCδ),12δ(CβCγCδ) B 30δ(CδCγCδ),16δ(CβCγCδ) A 32δ(CδCγCδ),18δ(CβCγCδ) B 30δ(CβCγCδ),16δ(NCαCβ) A 36δ(CβCγCδ),12δ(NCαCβ) B 34δ(CβCγCδ) A 38δ(CβCγCδ) A 24δ(CβCγCδ),24δ(NCαCβ),22δ(CδCγCδ) B 28δ(CβCγCδ),20δ(NCαCβ),16δ(CδCγCδ) B 24δ(CβCγCδ),20δ(CδCγCδ),18δ(NCαCβ) A 26δ(CβCγCδ),24δ(CδCγCδ),22δ(NCαCβ) B 20δ(CCαCβ),16δ(NCαC),12δ(CδCγCδ) B 30ρ(CO 2 ),24δ(NCαC) A 40δ(NCαC),30ρ(CO 2 ) A 24δ(CδCγCδ),18δ(NCαCβ),16δ(CβCγCδ) B 24δ(CδCγCδ),14δ(CβCγCδ),14δ(NCαCβ) A 24δ(NCαCβ),18δ(CδCγCδ),18δ(CβCγCδ) A 40δ(NCαC),34ρ(CO 2 ) B 38δ(NCαC),36ρ(CO 2 ) B 38δ(CCαCβ),16τ(CδH 3 ) A 36τ(CδH 3 ),24δ(CCαCβ),12δ(CβCγCδ) A 26δ(CCαCβ),22τ(CδH 3 ),12δ(CβCγCδ) B 40τ(CδH 3 ),16δ(CCαCβ) B 18δ(CαCβCγ),18rot,14δ(CβCγCδ) A 28δ(CαCβCγ),24rot,18δ(CβCγCδ) B 32τ(CδH 3 ),16δ(CαCβCγ),14rot A 30τ(CδH 3 ),16rot,14δ(CCαCβ) A 24δ(CCαCβ),22τ(CδH 3 ) B 38τ(CδH 3 ),14δ(CαCβCγ) A 48τ(CδH 3 ),12δ(CαCβCγ),12δ(CβCγCδ) B 42τ(CδH 3 ),22δ(CCαCβ) B 88τ(CδH 3 ) A 78τ(CδH 3 ) B 80τ(CδH 3 ) A 80τ(CδH 3 ) B 20rot,14τ(CO 2 ) B 40τ(CO 2 ),20rot A 58τ(CO 2 ) A 22rot,18τ(CαCβ),16δ(CαCβCγ) A 22τ(CO 2 ),22τ(CαCβ),16rot A 52τ(CO 2 ) B 30τ(CO 2 ),20τ(CαCβ),12δ(CαCβCγ) B 24δ(CαCβCγ),18τ(CO 2 ),14τ(CαCβ) B 42τ(CO 2 ),14rot,12τ(CαCβ) A 26τ(CβCγ),18rot B 58τ(CβCγ) A 32τ(CβCγ),20,14τ(CαCβ) B 44,28τ(CβCγ) A 38τ(CβCγ),18rot, A 32,28rot,12τ(CβCγ) B 32rot, B 38rot,28,18τ(CαCβ) A 38rot, A 30τ(CαCβ),28,22rot B 70rot A 42rot,14τ(CβCγ),14,12τ(CαCβ) B 32τ(CβCγ),28,18rot A 34rot,14τ(CO 2 ), B 48,18rot A B 28rot,22,18τ(CαCβ),12τ(CβCγ) A 38,38rot B 48,38rot A 52,26rot A 28τ(CαCβ),24,20rot B 30τ(CαCβ),22,16rot A B B 60,16rot A 52,20rot B 44,18rot 18

19 Table S16: Calculated frequencies, infrared intensities, irreducible group representation, and potential energy disibutions for L-isoleucine zwitterion. number freq. IR int. irrep. P.E.D. (greater than 10%) (cm 1 ) ((D/Å) 2 /u) A 32ρ(Cγ1H 2 ),14ρ(CδH 3 ) B 32ρ(Cγ1H 2 ),14ρ(CδH 3 ) B 38ω(CO 2 ),12ν(CαCβ) A 38ω(CO 2 ),12ν(CαCβ) B 48δ(CO 2 ) A 48δ(CO 2 ) B 24δ(CO 2 ),22δ(NCαC),12ω(CO2 ) A 24δ(CO 2 ),22δ(NCαC),12ρ(CO2 ),12ω(CO2 ) B + 78τ(NH 3 ) A + 82τ(NH 3 ) A + 60τ(NH 3 ) B + 74τ(NH 3 ) B 22ρ(CO 2 ),18δ(NCαCβ),14ν(NCα) A + 28τ(NH 3 ),16ρ(CO2 ),14δ(NCαCβ) B 18ρ(CO 2 ),18ν(CαC),14δ(CO2 ),12ν(NCα) A 18ν(CαC),16ρ(CO 2 ),14δ(CO2 ),14ν(NCα) A 28δ(CαCβCγ2),14ω(CO 2 ) B 28δ(CαCβCγ2),14ω(CO 2 ) B 28δ(CγCβCγ),12δ(NCαCβ) A 32δ(CγCβCγ) B 24δ(CγCβCγ),18δ(NCαCβ),12ρ(CO 2 ) A 26δ(CγCβCγ),16δ(NCαCβ),12ρ(CO 2 ) B 30δ(CαCβCγ2),16δ(CβCγ1Cδ),12ν(CαCβ) A 34δ(CαCβCγ2),16δ(CβCγ1Cδ),12ν(CαCβ) B 18δ(CγCβCγ),16δ(NCαC),16δ(NCαCβ),14ν(CαC) A 20δ(CγCβCγ),18δ(NCαCβ),16ν(CαC),14δ(NCαC) B 16δ(CβCγ1Cδ),14δ(CγCβCγ),14δ(NCαCβ) A 18δ(CβCγ1Cδ),16δ(NCαCβ) B 30ρ(CO 2 ),16δ(NCαC) A 36ρ(CO 2 ),32δ(NCαC) B 24δ(CαCβCγ2),18δ(CβCγ1Cδ) A 28δ(CβCγ1Cδ),18δ(CαCβCγ2) B 16δ(CγCβCγ),16δ(NCαC),12δ(NCαCβ) A 16δ(NCαC),14ρ(CO 2 ),14δ(CγCβCγ),14δ(NCαCβ) A 14τ(Cγ2H 3 ),14δ(CγCβCγ),12δ(CαCβCγ2) B 20δ(NCαC),18ρ(CO 2 ),12τ(Cγ2H3 ) B 20δ(CαCβCγ1),12δ(CβCγ1Cδ) A 24δ(CαCβCγ1),18δ(CγCβCγ),12δ(CCαCβ) A 44τ(Cγ2H 3 ),14τ(CδH 3 ) B 32τ(Cγ2H 3 ),12δ(CCαCβ) B 24δ(CCαCβ),14τ(Cγ2H 3 ) A 24τ(CδH 3 ),20δ(CCαCβ),16δ(CαCβCγ2) B 34τ(CδH 3 ),18δ(CαCβCγ2) A 30δ(CCαCβ),14δ(CαCβCγ2) B 26δ(CCαCβ) A 16δ(CCαCβ),14τ(CαCβ) A 48τ(CO 2 ) B 42τ(CO 2 ),12δ(CαCβCγ1) A 24τ(Cγ2H 3 ),20δ(CαCβCγ1),12τ(CδH 3 ),12δ(CβCγ1Cδ) B 40τ(CδH 3 ),26τ(Cγ2H 3 ) A 50τ(CδH 3 ) B 16τ(CδH 3 ),16τ(CO 2 ),14δ(CαCβCγ1) B 20τ(CδH 3 ),16τ(CO 2 ),16δ(CαCβCγ1) A 22τ(CO 2 ),20τ(CδH3 ),16τ(Cγ2H 3 ) B 44τ(Cγ2H 3 ),12τ(CδH 3 ),12τ(CO 2 ) A 36τ(Cγ2H 3 ),26τ(CO 2 ) B 40τ(CO 2 ) A 26τ(CO 2 ),26rot,14τ(CαCβ) B 32rot,18τ(CαCβ),12τ(CβCγ1) A 32rot,16,14τ(CαCβ) A 28τ(CβCγ1),28rot B 36rot,24τ(CαCβ) B 56τ(CβCγ1),16rot A 32τ(CβCγ1), A 50τ(CβCγ1),12rot B 36τ(CβCγ1),20rot, A 42rot, B 44rot,30τ(CαCβ) A 40τ(CαCβ) B 52,16rot A 52rot B 30rot,22,20τ(CαCβ) A 44,16rot B 42rot,28τ(CβCγ1) A 28,20rot,18τ(CαCβ) B 40rot,22,22τ(CαCβ) B 40rot, A A 36rot, B A 34,34rot B 52,20rot A 36,32rot B 56,28rot A 62,30rot B 64,26rot A 70,20rot B 58,20rot 19

20 Table S17: Far infrared experimental frequencies and intensities, assignments, and groups of calculated mode frequencies and symmey, for β glycine zwitterion. exp. calc. freq. b nb. a freq. b int. c assign. d A B δ(co 2 ) m τ(nh + 3 ) m ω(co 2 ) m ρ(co 2 ) m,b δ(ncαc) vs rot s rot rot s τ(co 2 ) w a Index based on lowest frequency of calculated mode groups b Wavenumber (cm 1 ) c Qualitative intensity: very song (vs), song (s), medium (m), weak (w), very weak (vw), shoulder (sh), broad (b) d Mode definitions: ν (setching), δ (bending), ρ (rocking), t (twisting), ω (wagging), and τ (torsion). 20

21 Table S18: Far infrared experimental frequencies and intensities, assignments, and groups of calculated mode frequencies and symmey, for α glycine zwitterion. exp. calc. freq. nb. freq. int. assign. Ag Bg Au Bu δ(co 2 ) sh τ(nh + 3 ) m ω(co 2 ) m ρ(co 2 ) m δ(ncαc) sh rot sh rot s τ(co 2 ) s rot w

22 Table S19: Far infrared experimental frequencies and intensities, assignments, and groups of calculated mode frequencies and symmey, for glycine cation. exp. calc. freq. nb. freq. int. assign. Ag Bg Au Bu w δ(co 2 H) ω(co 2 H) m ρ(co 2 H) τ(nh + 3 )/ν a(cl HN) m δ(ncαc) ν s(cl HN) ν s(cl HN)/τ(CO 2 ) s rot/ν(cl HO) s τ(co 2 H)/τ(NH + 3 ) rot/ν a(cl HN) ν(cl HO)/τ(CO 2 H)/rot m rot

23 Table S20: Far infrared experimental frequencies and intensities, assignments, and groups of calculated mode frequencies and symmey, for glycine anion. exp. calc. freq. nb. freq. int. assign. A B1 B2 B m δ(co 2 ) w ω(co 2 ) m ν(ona + ) w,b rot/δ(cona + ) ν(cona + )/δ(cona + ) w rot/τ(cona + ) m τ(nh 2 ) m δ(ncαc)/ρ(co 2 ) vs /δ(cona + ) τ(co 2 )/rot s τ(cona + ) m τ(co 2 )/rot m /rot /rot

24 Table S21: Far infrared experimental frequencies and intensities, assignments, and groups of calculated mode frequencies and symmey, for L-alanine zwitterion. exp. calc. freq. nb. freq. int. assign. A B1 B2 B ω(co 2 ) m δ(co 2 )/δ(ncαc) w τ(nh + 3 ) s ρ(co 2 ) s δ(ncαcβ) m δ(ncαc)/ρ(co 2 ) m δ(ccαcβ) w τ(cβh 3 ) sh rot m τ(co 2 ) m rot rot w w

25 Table S22: Far infrared experimental frequencies and intensities, assignments, and groups of calculated mode frequencies and symmey, for L-valine zwitterion. exp. calc. freq. nb. freq. int. assign. A B δ(co 2 ) ω(co 2 ) δ(co 2 ) m δ(ncαc)/δ(co 2 )/ ω(co 2 ) w τ(nh + 3 ) w τ(nh + 3 ) s ρ(co 2 ) s ρ(co 2 ) w δ(cαcβcγ) sh δ(ncαcβ) m δ(ncαcβ) m δ(cγcβcγ) s δ(cαcβcγ) δ(cγcβcγ) δ(ncαc)/ρ(co 2 ) s δ(cαcβcγ) m δ(ncαc)/ρ(co 2 ) m δ(ccαcβ) τ(cγh 3 ) δ(cαcβcγ)/δ(ccαcβ) τ(cγh 3 )/δ(cαcβcγ)/ τ(co 2 ) τ(cγh 3 ) τ(cγh 3 ) m τ(co 2 ) sh τ(cαcβ)/τ(cγh 3 ) τ(co 2 ) s τ(cγh 3 )/rot rot s τ(cαcβ) rot/τ(cαcβ) sh rot rot τ(cαcβ)/rot m vw w /rot

26 Table S23: Far infrared experimental frequencies and intensities, assignments, and groups of calculated mode frequencies and symmey, for L-leucine zwitterion. exp. calc. freq. nb. freq. int. assign. A B ω(co 2 ) ω(co 2 ) m δ(co 2 ) m δ(co 2 ) vw τ(nh + 3 ) vw τ(nh + 3 ) s ρ(co 2 ) s ρ(co 2 ) sh δ(cδcγcδ) sh δ(cδcγcδ) m δ(cβcγcδ) m δ(cβcγcδ) s δ(cβcγcδ) s δ(cβcγcδ) m δ(ncαc)/ρ(co 2 ) s δ(cδcγcδ)/ρ(co 2 )/ δ(ncαcβ) s δ(cδcγcδ)/δ(ncαcβ)/ δ(cβcγcδ) δ(ncαc)/ρ(co 2 ) δ(ccαcβ)/τ(cδh 3 ) τ(cδh 3 )/δ(ccαcβ) m δ(cαcβcγ)/rot s τ(cδh 3 ) τ(cδh 3 )/δ(cαcβcγ) τ(cδh 3 )/δ(ccαcβ) τ(cδh 3 ) τ(cδh 3 ) m τ(co 2 ) τ(co 2 ) sh τ(co 2 )/τ(cαcβ) δ(cαcβcγ)/τ(cαcβ) s rot/τ(co 2 )/ τ(cβcγ) sh τ(cβcγ) τ(cβcγ)/ rot/ τ(cαcβ)/rot/ rot rot/τ(cβcγ) /rot /rot τ(cαcβ)// rot

27 Table S24: Far infrared experimental frequencies and intensities, assignments, and groups of calculated mode frequencies and symmey, for L-isoleucine zwitterion. exp. calc. freq. nb. freq. int. assign. A B ρ(cγ1h 2 ) ω(co 2 ) δ(co 2 ) m δ(co 2 )/δ(ncαc) w,b τ(nh + 3 ) w,b τ(nh + 3 ) m ρ(co 2 )/δ(ncαcβ) s ρ(co 2 )/ν(cαc) w,b δ(cαcβcγ2) s δ(cγcβcγ) s δ(cγcβcγ) m δ(cαcβcγ2) s δ(cγcβcγ)/δ(ncαcβ) m δ(cβcγ1cδ)/δ(ncαcβ) s ρ(co 2 )/δ(ncαc) δ(cβcγ1cδ)/δ(cαcβcγ2) m δ(ncαc)/δ(cγcβcγ)/ δ(ncαcβ) τ(cγ2h 3 )/δ(ncαc)/ ρ(co 2 ) vw δ(cαcβcγ1) s,b τ(cγ2h 3 ) sh δ(ccαcβ) vw δ(ccαcβ) τ(cδh 3 )/δ(ccαcβ) sh τ(co 2 ) τ(cδh 3 )/τ(cγ2h 3 ) s τ(cδh 3 ) τ(co 2 )/τ(cδh 3 ) τ(cγ2h 3 ) τ(co 2 ) s rot rot sh τ(cβcγ1) τ(cβcγ1) τ(cαcβ) rot rot rot// τ(cαcβ) rot/ /rot

28 Intensity ((D/Å) 2 /u) δ(co 2 ) 600 τ(nh 3 + ) 608 ω(co 2 ) 521 Wavenumber (cm 1 ) ρ(co 2 ) δ(ncαc) rot rot rot τ(co 2 ) CALC glycine beta zwitterion EXP glycine ph6.6 (scaled) 61 0 Figure S2: Experimental (blue) and calculated (red) infrared speca for glycine β. Experimental band center frequencies are labelled. Calculated modes are annotated with the vibrations conibuting the most to the potential energy disibution. 28

29 Intensity ((D/Å) 2 /u) δ(co 2 ) τ(nh 3 + ) 600 ω(co 2 ) Wavenumber (cm 1 ) ρ(co 2 ) δ(ncαc) rot rot τ(co 2 ) rot CALC glycine alpha zwitterion EXP glycine powder (scaled) 62 0 Figure S3: Experimental (blue) and calculated (red) infrared speca for glycine α. Experimental band center frequencies are labelled. Calculated modes are annotated with the vibrations conibuting the most to the potential energy disibution. 29

30 Intensity ((D/Å) 2 /u) δ(co 2 H) ω(co 2 H) 500 ρ(co 2 H) Wavenumber (cm 1 ) τ(nh 3 + )/νa (Cl HN) δ(ncαc) ν s (Cl HN) ν s (Cl HN)/τ(CO 2 ) rot/ν(cl HO) τ(co 2 H)/τ(NH 3 + ) rot/ν a (Cl HN) ν(cl HO)/τ(CO 2 H)/rot rot CALC glycine cation Cl EXP glycine ph1.1 (scaled) 0 Figure S4: Experimental (blue) and calculated (red) infrared speca for glycine cation. Experimental band center frequencies are labelled. Calculated modes are annotated with the vibrations conibuting the most to the potential energy disibution. 30

31 Intensity ((D/Å) 2 /u) δ(co 2 ) ω(co 2 ) 580 ν(ona + ) 500 rot/δ(cona + ) ν(cona + )/δ(cona + ) Wavenumber (cm 1 ) rot/τ(cona + ) τ(nh 2 ) δ(ncαc)/ρ(co 2 ) /δ(cona + ) τ(co 2 )/rot τ(cona + ) τ(co 2 )/rot /rot CALC glycine anion Na + EXP glycine ph13.0 (scaled) /rot 0 Figure S5: Experimental (blue) and calculated (red) infrared speca for glycine anion. Experimental band center frequencies are labelled. Calculated modes are annotated with the vibrations conibuting the most to the potential energy disibution. 31

32 Intensity ((D/Å) 2 /u) ω(co 2 ) 700 δ(co 2 )/δ(ncαc) τ(nh 3 + ) ρ(co 2 ) Wavenumber (cm 1 ) δ(ncαcβ) δ(ncαc)/ρ(co 2 ) δ(ccαcβ) τ(cβh 3 ) rot τ(co 2 ) rot rot CALC Lalanine zwitterion EXP Lalanine ph6.5 (scaled) 0 Figure S6: Experimental (blue) and calculated (red) infrared speca for L-alanine. Experimental band center frequencies are labelled. Calculated modes are annotated with the vibrations conibuting the most to the potential energy disibution. 32

33 Intensity ((D/Å) 2 /u) δ(co 2 ) 700 ω(co 2 ) δ(co 2 ) δ(ncαc)/δ(co 2 )/ω(co2 ) τ(nh 3 + ) τ(nh 3 + ) ρ(co 2 ) ρ(co 2 ) Wavenumber (cm 1 ) δ(cαcβcγ) δ(ncαcβ) δ(ncαcβ) δ(cγcβcγ) δ(cαcβcγ) δ(cγcβcγ) δ(ncαc)/ρ(co 2 ) δ(cαcβcγ) δ(ncαc)/ρ(co 2 ) δ(ccαcβ) τ(cγh 3 ) δ(cαcβcγ)/δ(ccαcβ) τ(cγh 3 )/δ(cαcβcγ)/τ(co 2 ) τ(cγh 3 ) τ(cγh 3 ) τ(co 2 ) τ(cαcβ)/τ(cγh 3 ) τ(co 2 ) τ(cγh 3 )/rot rot τ(cαcβ) rot/τ(cαcβ) rot rot τ(cαcβ)/rot /rot CALC Lvaline zwitterion EXP Lvaline ph6.3 (scaled) 0 Figure S7: Experimental (blue) and calculated (red) infrared speca for L-valine. Experimental band center frequencies are labelled. Calculated modes are annotated with the vibrations conibuting the most to the potential energy disibution. 33

34 Intensity ((D/Å) 2 /u) ω(co 2 ) ω(co 2 ) 700 δ(co 2 ) δ(co 2 ) τ(nh 3 + ) τ(nh 3 + ) ρ(co 2 ) ρ(co 2 ) Wavenumber (cm 1 ) δ(cδcγcδ) δ(cδcγcδ) δ(cβcγcδ) δ(cβcγcδ) δ(cβcγcδ) δ(cβcγcδ) δ(ncαc)/ρ(co 2 ) δ(cδcγcδ)/ρ(co 2 )/δ(ncαcβ) δ(cδcγcδ)/δ(ncαcβ)/δ(cβcγcδ) δ(ncαc)/ρ(co 2 ) δ(ccαcβ)/τ(cδh 3 ) τ(cδh 3 )/δ(ccαcβ) δ(cαcβcγ)/rot τ(cδh 3 ) τ(cδh 3 )/δ(cαcβcγ) τ(cδh 3 )/δ(ccαcβ) τ(cδh 3 ) τ(cδh 3 ) τ(co 2 ) τ(co 2 ) τ(co 2 )/τ(cαcβ) δ(cαcβcγ)/τ(cαcβ) rot/τ(co 2 )/τ(cβcγ) τ(cβcγ) τ(cβcγ)/ rot/ τ(cαcβ)/rot/ rot rot/τ(cβcγ) /rot /rot τ(cαcβ)//rot CALC Lleucine zwitterion EXP Lleucine ph6.4 (scaled) 0 Figure S8: Experimental (blue) and calculated (red) infrared speca for L-leucine. Experimental band center frequencies are labelled. Calculated modes are annotated with the vibrations conibuting the most to the potential energy disibution. 34