02590nas a2200241 4500008004100000022001400041245020000055210006900255260007700324300001400401490000700415520160100422653001902023653001302042653002602055653002602081653002402107100001902131700002402150700002302174700002502197856012602222 2005 eng d a0947-653900aBenzoyl transfer reactivities of racemic 2,4-Di-O-acyl-myo-inosityl 1,3,5-orthoesters in the solid state: molecular packing and intermolecular interactions correlate with the ease of the reaction0 aBenzoyl transfer reactivities of racemic 24DiOacylmyoinosityl 13 aPO BOX 10 11 61, D-69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcMAR a2103-21100 v113 a

Racemic 2,4-di-O-acyl-myoinosityl 1,3,5-orthoesters undergo transesterification catalyzed by sodium carbonate with varying ease of reaction in the solid state; reactions in solution and melt do not show such varied differences. An interesting crystal of a 1:1 molecular complex of highly reactive racemic 2,4-di-O-benzoyl-myo-inosityl 1,3,5-orthoformate and its orthoacetate analogue exhibited better reactivity than the latter component alone. Single-crystal X-ray structures of the reactants have been correlated with the observed differences in the acyl-transfer efficiencies in the solid state. Although each of the derivatives helically self-assembles around the crystallographic 2(1) axis linked through O-(HO)-O-... hydrogen bonding, the pre-organization of the reactive groups (C=O [El] and OH [Nu]), C-(HO)-O-... and the C=H(...)pi interactions are significantly more favourable for the reactive derivatives than the less reactive ones. Bond-length distributions also showed differences; the O-C bond of the axial benzoyl group, which gets cleaved during the reaction, is longer (1.345-1.361 angstrom) relative to the chemically equivalent O-C bond of the equatorial benzoyl group (1.316-1.344 angstrom) in the reactive derivatives. These bond-length differences are not significant in the less reactive derivatives. The overall molecular organization is different too; the strikingly discrete helices, which may be viewed as ``reaction tunnels'' and are held by interhelical interactions, are clearly evident in the reactive derivatives in comparison with the less reactive ones.

10ahydrogen bonds10aInositol10asolid-state reactions10astructure elucidation10atransesterification1 aSarmah, M., P.1 aGonnade, Rajesh, G.1 aShashidhar, M., S.1 aBhadbhade, Mohan, M. uhttp://library.ncl.res.in/content/benzoyl-transfer-reactivities-racemic-24-di-o-acyl-myo-inosityl-135-orthoesters-solid-101812nas a2200265 4500008004100000022001400041245013800055210006900193260007500262300001400337520077500351653002601126653001901152653002001171653002601191100002401217700003301241700002201274700002201296700002301318700002401341700002401365700002801389856012901417 2016 eng d a1434-193X00aDisruption of native beta-turns: consequence of folding competition between native and orthanilic acid proline-based pseudo beta-turn0 aDisruption of native betaturns consequence of folding competitio aPOSTFACH 101161, 69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcMAR a1380-13883 a

Five tetrapeptides comprising beta-turn-forming elements and a pseudo beta-turn (C9 H-bonding) based on an SAntPro (orthanilic acid - proline) motif were designed and synthesized. Their extensive conformational investigation by single-crystal X-ray crystallography, solution-state 2D NMR spectroscopic, and nOe-restrained MD simulation studies revealed the formation of C14 or C9 folding and disruption of the native beta-turn (C10 H-bonding) architecture. The striking difference between the psi(psi(2)) angle of ``i + 2'' residues of native beta-turn and designed peptides suggest that formation of the native beta-turn is not favored. The results suggest that other turn-forming motifs can dramatically modulate the stability of the native beta-turn structure.

10aConformation analysis10ahydrogen bonds10aPeptidomimetics10astructure elucidation1 aIngole, Tukaram, S.1 aVijayadas, Kuruppanthara, N.1 aChaitanya, K., N.1 aKotmale, Amol, S.1 aGawade, Rupesh, L.1 aGonnade, Rajesh, G.1 aRajamohanan, P., R.1 aSanjayan, Gangadhar, J. uhttp://library.ncl.res.in/content/disruption-native-beta-turns-consequence-folding-competition-between-native-and-orthanilic02532nas a2200277 4500008004100000245016800041210006900209260000800278300001200286490000700298520154600305653003001851653001901881653002101900653002201921653001601943653001501959100002401974700002501998700002402023700002402047700001702071700002402088700002402112856011802136 2020 eng d00aFive concomitant polymorphs of a green fluorescent protein chromophore (GFPc) analogue: understanding variations in photoluminescence with pi-stacking interactions0 aFive concomitant polymorphs of a green fluorescent protein chrom cOCT a850-8640 v763 a

The synthetically modified green fluorescent protein chromophore analogue 3,4,5-trimethoxybenzylidene imidazolinone (1) yielded five polymorphs (I, II, III, IV, V) concomitantly irrespective of the solvent used for crystallization. The pentamorphic modification of 1 is solely due to the interplay of iso-energetic weak intermolecular interactions in molecular associations as well as the conformational flexibility offered by a C-C single bond, which connects the electron-deficient moiety imidazolinone with the electron-rich trimethoxybenzylidene group. A common structural feature observed in all the polymorphs is the formation of a `zero-dimensional' centrosymmetric dimeric unit through a short and linear C-H center dot center dot center dot O hydrogen bond engaging phenyl C-H and imidazolinone carbonyl oxygen. However, the networking of these dimeric units showed a subtle difference in all the polymorphs. The 2D isostructurality was observed between polymorphs I, II and III, while the other two polymorphs IV and V revealed only `zero-dimensional' isostructurality. The different fluorescence emissions of Form I (blue) and Forms II to V (yellow) were attributed to the differences in pi-stacking interactions. It shows that one can modulate the photophysical properties of these smart materials by slightly altering their crystal structure. Such an approach will aid in developing new multi-colour organic fluorescent materials of varying crystal structures for live-cell imaging and fluorescent sensing applications.

10agreen fluorescent protein10ahydrogen bonds10aisostructurality10aphotoluminescence10api-stacking10aPolymorphs1 aMali, Bhupendra, P.1 aDash, Soumya, Ranjan1 aNikam, Shrikant, B.1 aPuthuvakkal, Anisha1 aVanka, Kumar1 aManoj, Kochunnoonny1 aGonnade, Rajesh, G. uhttp://library.ncl.res.in/content/five-concomitant-polymorphs-green-fluorescent-protein-chromophore-gfpc-analogue