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1. O -Benzoyl side-chain conformations in 2,3,4,6-tetra- O -benzoyl-β- D -galactopyranosyl-(1→4)-1,2,6-tri- O -benzoyl-β- D -glucopyranose (ethyl acetate solvate) and 1,2,4,6-tetra- O -benzoyl-β- D -glucopyranose (acetone solvate)

   https://doi.org/10.1107/S2053229619000822  

   Turney, Toby; Pan, Qingfeng; Zhang, Wenhui; Oliver, Allen G.; Serianni, Anthony S. (February 2019, Acta Crystallographica Section C Structural Chemistry)

   The crystal structures of 2,3,4,6-tetra- O -benzoyl-β-D-galactopyranosyl-(1→4)-1,2,6-tri- O -benzoyl-β-D-glucopyranose ethyl acetate hemisolvate, C 61 H 50 O 18 ·0.5C 4 H 8 O 2 , and 1,2,4,6-tetra- O -benzoyl-β-D-glucopyranose acetone monosolvate, C 34 H 28 O 10 ·C 3 H 6 O, were determined and compared to those of methyl β-D-galactopyranosyl-(1→4)-β-D-glucopyranoside (methyl β-lactoside) and methyl β-D-glucopyranoside hemihydrate, C 7 H 14 O 6 ·0.5H 2 O, to evaluate the effects of O -benzoylation on bond lengths, bond angles and torsion angles. In general, O -benzoylation exerts little effect on exo- and endocyclic C—C and endocyclic C—O bond lengths, but exocyclic C—O bonds involved in O -benzoylation are lengthened by 0.02–0.04 Å depending on the site of substitution. The conformation of the O -benzoyl side-chains is highly conserved, with the carbonyl O atom either eclipsing the H atom attached to a 2°-alcoholic C atom or bisecting the H—C—H bond angle of an 1°-alcoholic C atom. Of the three bonds that determine the side-chain geometry, the C—O bond involving the alcoholic C atom exhibits greater rotational variability than the remaining C—O and C—C bonds involving the carbonyl C atom. These findings are in good agreement with recent solution NMR studies of the O -acetyl side-chain conformation in saccharides. 

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2. Methyl β-lactoside [methyl β- D -galactopyranosyl-(1→4)-β- D -glucopyranoside] monohydrate: a solvomorphism study

   https://doi.org/10.1107/S2053229621009499  

   Lin, Jieye; Oliver, Allen G.; Serianni, Anthony S. (October 2021, Acta Crystallographica Section C Structural Chemistry)

   Methyl β-lactoside [methyl β-D-galactopyranosyl-(1→4)-β-D-glucopyranoside] monohydrate, C 13 H 24 O 11 ·H 2 O, (I), was obtained via spontaneous transformation of methyl β-lactoside methanol solvate, (II), during air-drying. Cremer–Pople puckering parameters indicate that the β-D-Gal p (β-D-galactopyranosyl) and β-D-Glc p (β-D-glucopyranosyl) rings in (I) adopt slightly distorted 4 C 1 chair conformations, with the former distorted towards a boat form ( B C1,C4 ) and the latter towards a twist-boat form ( O5 S C2 ). Puckering parameters for (I) and (II) indicate that the conformation of the βGal p ring is slightly more affected than the βGlc p ring by the solvomorphism. Conformations of the terminal O -glycosidic linkages in (I) and (II) are virtually identical, whereas those of the internal O -glycosidic linkage show torsion-angle changes of 6° in both C—O bonds. The exocyclic hydroxymethyl group in the βGal p residue adopts a gt conformation (C4′ anti to O6′) in both (I) and (II), whereas that in the βGlc p residue adopts a gg ( gauche – gauche ) conformation (H5 anti to O6) in (II) and a gt ( gauche – trans ) conformation (C4 anti to O6) in (I). The latter conformational change is critical to the solvomorphism in that it allows water to participate in three hydrogen bonds in (I) as opposed to only two hydrogen bonds in (II), potentially producing a more energetically stable structure for (I) than for (II). Visual inspection of the crystalline lattice of (II) reveals channels in which methanol solvent resides and through which solvent might exchange during solvomorphism. These channels are less apparent in the crystalline lattice of (I). 

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3. Classes of O–D centers in unintentionally and Fe-doped β-Ga2O3 annealed in a D2 ambient

   https://doi.org/10.1063/5.0160331  

   Portoff, Amanda; Venzie, Andrew; Stavola, Michael; Fowler, W. Beall; Glaser, Evan; Pearton, Stephen J. (July 2023, Journal of Applied Physics)

   β-Ga2O3 has attracted much recent attention as a promising ultrawide bandgap semiconductor. Hydrogen can affect the conductivity of β-Ga2O3 through the introduction of shallow donors and the passivation of deep acceptors. The introduction of H or D into β-Ga2O3 by annealing in an H2 or D2 ambient at elevated temperature produces different classes of O–H or O–D centers. This work is a study of the interaction of D with VGa1 and VGa2 deep acceptors as well as other impurities and native defects in Ga2O3 by infrared spectroscopy and the complementary theory. (We focus primarily on the deuterium isotope of hydrogen because the vibrational modes of O–D centers can be detected with a higher signal-to-noise ratio than those of O–H.) O–D centers in β-Ga2O3 evolve upon annealing in an inert ambient and are transformed from one type of O–D center into another. These reactions affect the compensation of unintentional shallow donors by deep acceptors that are passivated by D. Defects involving additional impurities in β-Ga2O3 compete with VGa deep acceptors for D and modify the deuterium-related reactions that occur. The defect reactions that occur when D is introduced by annealing in a D2 ambient appear to be simpler than those observed for other introduction methods and provide a foundation for understanding the D-related reactions that can occur in more complicated situations. 

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4. Conformational analysis of the disaccharide methyl α- D -mannopyranosyl-(1→3)-2- O -acetyl-β- D -mannopyranoside monohydrate

   https://doi.org/10.1107/S2053229619004728  

   Zhang, Wenhui; Wu, Qingquan; Oliver, Allen G.; Serianni, Anthony S. (June 2019, Acta Crystallographica Section C Structural Chemistry)

   The crystal structure of methyl α-D-mannopyranosyl-(1→3)-2- O -acetyl-β-D-mannopyranoside monohydrate, C 15 H 26 O 12 ·H 2 O, ( II ), has been determined and the structural parameters for its constituent α-D-mannopyranosyl residue compared with those for methyl α-D-mannopyranoside. Mono- O -acetylation appears to promote the crystallization of ( II ), inferred from the difficulty in crystallizing methyl α-D-mannopyranosyl-(1→3)-β-D-mannopyranoside despite repeated attempts. The conformational properties of the O -acetyl side chain in ( II ) are similar to those observed in recent studies of peracetylated mannose-containing oligosaccharides, having a preferred geometry in which the C2—H2 bond eclipses the C=O bond of the acetyl group. The C2—O2 bond in ( II ) elongates by ∼0.02 Å upon O -acetylation. The phi (φ) and psi (ψ) torsion angles that dictate the conformation of the internal O -glycosidic linkage in ( II ) are similar to those determined recently in aqueous solution by NMR spectroscopy for unacetylated ( II ) using the statistical program MA′AT , with a greater disparity found for ψ (Δ = ∼16°) than for φ (Δ = ∼6°). 

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5. Synthesis and Self-Assembling Properties of Peracetylated β-1-Triazolyl Alkyl D-Glucosides and D-Galactosides

   https://doi.org/10.3390/chemistry3030068  

   Sharma, Pooja; Chen, Anji; Wang, Dan; Wang, Guijun (September 2021, Chemistry)

   Carbohydrate-based low-molecular-weight gelators (LMWGs) are useful classes of compounds due to their numerous applications. Among sugar-based LMWGs, certain peracetylated sugar beta-triazole derivatives were found to be effective organogelators and showed interesting self-assembling properties. To further understand the structural influence towards molecular assemblies and obtain new functional materials with interesting properties, we designed and synthesized a library of tetraacetyl beta-1-triazolyl alkyl-D-glucosides and D-galactosides, in which a two or three carbon spacer is inserted between the anomeric position and the triazole moiety. A series of 16 glucose derivatives and 14 galactose derivatives were synthesized and analyzed. The self-assembling properties of these new triazole containing glycoconjugates in different solvents were analyzed. Several glucose derivatives were found to be effective LMWGs, with compound 7a forming gels in a variety of organic solvents as well as in the presence of metal ions in aqueous solutions. The organogels formed by several compounds were characterized using optical microscopy, atomic force microscopy (AFM) and UV-vis spectroscopy, etc. The co-gels formed by compound 7a with the Fmoc derivative 7i showed interesting fluorescence enhancement upon gelation. Several gelators were also characterized using powder X-ray diffraction and FT-IR spectroscopy. The potential applications of these sugar-based gelators for drug delivery and dye removal were also studied. 

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