Shrinwantu Pal - Charge density analysis of two proton transfer complexes: Understanding hydrogen bonding and determination of in-crystal dipole moments

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      Publication Details (including relevant citation   information):

      An experimental charge density study has been carried out on   proton-transfer complexes exhibiting nonlinear optical (NLO)   properties-melaminium tartrate monohydrate and   l-asparaginium picrate employing high-resolution   X-ray diffraction at 100 K. Both the complexes crystallize in   non-centric space group P21 and the structures exhibit   interesting patterns of N-H…O and O-H…O hydrogen bonding.   Experimental determination of the dipole moment (µ) for the   asymmetric unit reveals that for both the crystals, there is a   large cooperative enhancement in the crystalline µ arising   essentially due to hydrogen bond mediated charge transfer between   the melaminium ion and the l-tartrate in one case,   between the l-asparaginium ion and the picrate in   the other complex. We have additionally performed theoretical   calculations at the density functional theory (DFT) level to   understand the origin of enhancement of the dipole moments in the   two systems.

      Abstract:

      An experimental charge density study has been carried out on   proton-transfer complexes exhibiting nonlinear optical (NLO)   properties-melaminium tartrate monohydrate and   l-asparaginium picrate employing high-resolution   X-ray diffraction at 100 K. Both the complexes crystallize in   non-centric space group P21 and the structures exhibit   interesting patterns of N-H…O and O-H…O hydrogen bonding.   Experimental determination of the dipole moment (µ) for the   asymmetric unit reveals that for both the crystals, there is a   large cooperative enhancement in the crystalline µ arising   essentially due to hydrogen bond mediated charge transfer between   the melaminium ion and the l-tartrate in one case,   between the l-asparaginium ion and the picrate in   the other complex. We have additionally performed theoretical   calculations at the density functional theory (DFT) level to   understand the origin of enhancement of the dipole moments in the   two systems.

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