File Name : fig_s1.tif

Caption : fig. s1 graphical interpretation of the δpka rule25 in the case of glycine salts and co-crystals.

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Caption : fig. s2 homomolecular interactions in the structures of gta (a-c) and gph (d,f). the structure of gta contains two types of homomolecular contacts: (a) glycine zwitterionic chains and (b,c) dl-tartaric acid dimeric chains, whereas gph has only glycine zwitterionic layers (d, f). phthalic acid molecules are omitted for clarity. 

File Name : fig_s3.tif

Caption : fig. s3 unit cell parameters and volume of gta at different temperatures. 

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Caption : fig. s4 unit cell parameters and volume of gph at different temperatures.

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Caption : fig. s5 unit cell diagrams highlighting hydrogen bond expanding on cooling (o3-h3...o2 [x-1, y, z]) and a dependence of a donor-acceptor distance from temperature for gta. these plots are based on low temperature single crystal x-ray diffraction data. glycine is green, tartaric acid is blue. 

File Name : fig_s6.tif

Caption : fig. s6 the dependence of the distances between non-hydrogen atoms in the hydrogen bonds in gta (a) and gph (b). all bonds become shorter except o3-h3...o2 [x-1, y, z] hydrogen bond in gta on cooling to 100 k.

File Name : fig_s7.tif

Caption : fig. s7 linear strain along the principal axes of the strain ellipsoid vs. temperature. (a) gta and (b) gph. ambient temperature is taken as a reference point. 

File Name : fig_s8.tif

Caption : fig. s8 the directions (indicated by arrows) of the principal axes of the strain ellipsoid with respect to the hydrogen bond network of the gta structure in low temperature experiments (see also fig. s7). glycine – green, tartaric acid – blue. 

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Caption : fig. s9 the directions (indicated by arrows) of the principal axes of the strain ellipsoid with respect to the hydrogen bond network of the gph structure in low temperature experiments (see also fig.s7). phthalic acid is not shown at the plot b) for clarity.

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Caption : fig. s10 structural changes as a result of the phase transition in gga at low temperature and at high pressure.<sup>33,34</sup>

File Name : fig_s11.tif

Caption : fig. s11 a) linear strain along the principal axes of the strain ellipsoid (in accordance with table s2) vs. pressure for triclinic phase of gta. 0.4 gpa point is taken as a reference point. b) linear strain along the principal axes of the strain ellipsoid (the axes coincide with that of pictured in fig. s7 and fig. s9) vs. pressure for orthorhombic (ambient) phase of gph. 0 gpa point is taken as a reference point. 

File Name : fig_s12.tif

Caption : fig. s12 formation of a three-centered contact between two dl-tartaric acid molecules in the gta triclinic phase at increased pressure.

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Caption : fig. s13 a distance change between one of the glycine molecules and dl-tartaric acid molecules with increasing pressure. shortening of the n11…o11 [2-x, 2-y, 2-z] distance can be related to the strengthening of the interaction between glycine and the corresponding tartaric acid molecule.

File Name : fig_s14.tif

Caption : fig. s14 decomposition of a gta single crystal under direct laser beam during a raman spectroscopy experiment (at 0.1 gpa). a – before exposure, b – after exposure. 

