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L-Cysteine hydrogen fluoride, or bis(L-cysteinium) difluoride-L-cysteine-hydrogen fluoride (1/1/1), 2C3H8NO2S+·2F−·C3H7NO2S·HF or L-Cys+(L-Cys...L-Cys+)F−(F−...H-F), provides the first example of a structure with cations of the `triglycine sulfate' type, i.e. A+( A... A+) (where A and A+ are the zwitterionic and cationic states of an amino acid, respectively), without a doubly charged counter-ion. The salt crystallizes in the monoclinic system with the space group P21. The dimeric (L-Cys...L-Cys+) cation and the dimeric (F−...H-F) anion are formed via strong O-H...O or F-H...F hydrogen bonds, respectively, with very short O...O [2.4438 (19) Å] and F...F distances [2.2676 (17) Å]. The F...F distance is significantly shorter than in solid hydrogen fluoride. Additionally, there is another very short hydrogen bond, of O-H...F type, formed by a L-cysteinium cation and a fluoride ion. The corresponding O...F distance of 2.3412 (19) Å seems to be the shortest among O-H...F and F-H...O hydrogen bonds known to date. The single-crystal X-ray diffraction study was complemented by IR spectroscopy. Of special interest was the spectral region of vibrations related to the above-mentioned hydrogen bonds. [ABSTRACT FROM AUTHOR]

Four mixed salts of amino acid L-histidine comprising hexafluorosilicate anion have been obtained in form of single crystals. These mixed salts are: orthorhombic 2L-His2+⋅2ClO4-⋅SiF62-⋅2H2O (space group P21212, Z=2, a=10.1549(8) Å, b=14.847(1) Å, c=8.7536(7) Å, which is isostructural with recently published 2L-His2+⋅2BF4-⋅SiF62-⋅2H2O), monoclinic 2L-His2+⋅2Cl-⋅SiF62- (space group C2, Z=2, a=27.037(2) Å, b=6.9849(5) Å, c=5.3630(4) Å, β=91.928(4)°) and isostructural 2L-His2+⋅2Br-⋅SiF62- (space group C2, Z=2, a=27.063(6) Å, b=7.1013(17) Å, c=5.5076(11) Å, β=92.141(11)°), and triclinic 2L-His2+⋅SO42-⋅SiF62-⋅3H2O (space group P1, Z=1, a=8.5005(17) Å, b=8.7896(18) Å, c=9.7286(19) Å, α=71.49(3)°, β=92.141(11)°, γ=86.17(3)°). [ABSTRACT FROM AUTHOR]

The monoclinic crystal structure of tetrasarcosine potassium iodide dihydrate {or catena-poly[[potassium-tetra-μ-sarcosine-κ4 O: O′;κ4 O: O] iodide dihydrate]}, {[K(C3H7NO2)4]I·2H2O} n or Sar4·KI·2H2O (space group C2/ c), comprises two crystallographically different sarcosine molecules and one water molecule on general positions, and one K+ cation and one I− anion located on twofold axes. The irregular eight-coordinated K+ polyhedra are connected into infinite chains along [001] via sarcosine molecules. This compound is the first sarcosine metal halogenide salt with a 4:1 ratio. A short overview of other sarcosine metal halogenide salts is presented and relationships to similar glycine salts are discussed. [ABSTRACT FROM AUTHOR]

We argue that the IR and Ramanspectra of “Lalanine alaninium nitrate” given in “Investigation on the growth, optical behaviour and factor group of an NLO crystal: LAlanine Alaninium nitrate” by Aravindan et al., Cryst. Res. Technol. 42, 1097 2007, actually concern LAlanine. Correspondingly, the data presented in “A comparative study on the growth and characterization of nonlinear optical amino acid crystals: LAlanine LA and Lalanine alaninium nitrate LAAN” by Aravindan et al., Spectrochim. Acta A 71, 297 2008, seems to be erroneous, as is “Synthesis, Growth, and Characterization of a New Semiorganic Nonlinear Optical Crystal: LAlanine Sodium Nitrate LASN”, Sethuraman, et al., Cryst. Growth Des. 8, 1863 2008. In these papers properties and data were reported for LAlanine compounds that actually are LAlanine crystals and, in addition, unit cell parameters were given that seem to have been copied from other papers. © 2009 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim [ABSTRACT FROM AUTHOR]

• Alanine adipate is, in fact, adipic acid. • Adipic acid crystallizes in the centrosymmetric P 2 1 / c space group. • Crystal structure determination of new crystals is mandatory. We show that a recently published paper "Spectroscopic evaluation of Alanine Adipate nonlinear optical materials growth dynamics: Mechanical and thermal optimization" (S. Akilandeswari, L. Jothi, J. Mol. Struct. 1240 (2021) 130577) is completely erroneous. A so-called "alanine adipate" actually is adipic acid, which is centrosymmetric and therefore cannot be a nonlinear optical crystal showing second harmonic activity. [ABSTRACT FROM AUTHOR]

Single crystals of two new compounds, (L-CysH⋯L-Cys)(HC2O4) (I) and (L-CysH⋯L-Cys⋯L-CysH)(HC2O4)2·0.5H2O (II), were obtained. Crystal structures were solved and refined using single-crystal X-ray diffraction, and compared with the previously known orthorhombic and monoclinic modifications of the simple salt (L-CysH)(HC2O4). Compound I crystallizes in the triclinic crystal system (space group P1, Z = 2) and contains (L-CysH⋯L-Cys) dimeric cations with very short O⋯O interatomic distance of 2.434(2) Å. Hydrogen oxalate anions form head-to-tail type chains with very short hydrogen bonds, characterized by O⋯O distances of 2.422(2) Å and 2.417(3) Å. The crystal lattice of II is monoclinic with the space group C2, Z = 4. It contains a new type of cation, that has never been observed before for cysteine salts, i.e. trimeric (L-CysH⋯L-Cys⋯L-CysH) cation. Protonated L-cysteinium cations are connected to the zwitterionic L-cysteine moiety through the same oxygen atom of the carboxylate group via hydrogen bonds, with O···O distances of 2.6410(18) Å and 2.4888(19) Å. Similar to the structure I, the hydrogen oxalate anions form head-to-tail type chains linked by short hydrogen bonds with O⋯O distances of 2.4369(17) Å and 2.4330(17) Å, respectively. The crystals were characterized by IR and Raman spectroscopy. The batches obtained on crystallization were also characterized by X-ray powder diffraction, in order to check the phase purity of all the sample. [ABSTRACT FROM AUTHOR]

Two new salts of l-proline containing triiodide anions were obtained and investigated: (l-ProH···l-Pro)(I3) (I) and [(l-ProH)3(l-Pro)](I3)3 (II). Both compounds crystallize in the polar monoclinic space group P21. Crystal structure determinations showed that (I) contains a dimeric cation formed by an O-H···O hydrogen bond with an O···O distance of 2.458(4) Å, while (II) features a peculiar tetrameric cation [l-ProH···(l-Pro-H-l-Pro)···l-ProH], where (l-Pro-H-l-Pro) is a pseudocentrosymmetric dimer with a very short hydrogen bond with an O···O distance of 2.427 Å. Infrared spectra of both crystals were registered and interpreted based on their structures. Electronic band structures were determined by quantum chemical calculations. The CASTEP code was used to calculate the band structures, total and partial density of states (TDOS, PDOS). Bandgaps were also measured by the diffuse reflectance method. [ABSTRACT FROM AUTHOR]

We show that the papers on ‘L-threonine doped thiourea’ (Thilakavathi et al., Materials Research Innovations 20 (2016) 254–258) and on obtaining a compound ‘ureaL-threonine’ (Jaikumar and Kalainathan, Crystal Research Technology 43 (2008) 565–571) are completely erroneous. [ABSTRACT FROM PUBLISHER]

We prove that a so-called L-alanine barium nitrate NLO single crystal described by Suresh Kumar et al. (Materials Research Innovations, DOI:10.1080/14328917.2017.1323990) is a dubious crystal and the title paper is erroneous. [ABSTRACT FROM AUTHOR]