Equivalence of NH4+, NH2NH3+, and OHNH3+ in directing the noncentrosymmetric diamondoid network of O-H···O- hydrogen bonds in dihydrogen cyclohexane tricarboxylate

Bhogala, Balakrishna R. ; Vishweshwar, Peddy ; Nangia, Ashwini (2005) Equivalence of NH4+, NH2NH3+, and OHNH3+ in directing the noncentrosymmetric diamondoid network of O-H···O- hydrogen bonds in dihydrogen cyclohexane tricarboxylate Crystal Growth & Design, 5 (3). pp. 1271-1281. ISSN 1528-7483

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Official URL: http://pubs.acs.org/doi/abs/10.1021/cg0500270?prev...

Related URL: http://dx.doi.org/10.1021/cg0500270

Abstract

The assembly of hexagonal and diamond network architectures from functionalized tectons of trigonal and tetrahedral symmetry, respectively, is an important activity in crystal engineering. We report a novel supramolecular transformation for the synthesis of diamond network structures from the trigonal molecule, 1,3-cis,5-cis-cyclohexanetricarboxylic acid (H3CTA). Crystal structures of some salts of the trigonal anion, H2CTA-, with tetrahedral counterions is analyzed in H2CTA-·NH4+ 1, H2CTA-·MeNH3+ 2, H2CTA-·EtNH3+ 3, H2CTA-·NH2NH3+ 4, and H2CTA-·OHNH3+ 5. The trigonal anion functions as a tetrahedral self-complementary node in the presence of NH4+ counterion (salt 1) via two COOH donors and COO- as a double hydrogen-bond acceptor. The triply interpenetrated diamondoid network of O-H···O- hydrogen bonds in 1 is reproduced in isostructural 3D nets of 4 and 5 by substituting NH4+ by NH2NH3+ and OHNH3+ (η = 0.025, 0.027). The SHG activity of noncentrosymmetric diamondoid solids 1, 4, and 5 (space group Cc) is comparable to that of the nonlinear optical (NLO) material potassium dihydrogen phosphate (KDP) (0.3×urea). However, salts 2 and 3 (space groups P21/c and P) have hexagonal and square grid layers of H2CTA- anions because the ammonium cation in these structures is devoid of the fourth strong hydrogen-bond donor group to extend crystal growth to the 3D diamond network. Thus, RNH3+ counterions may be used to control the anionic network of the H2CTA- molecule based on a tetrahedral node in 1, 4, and 5, a trigonal node in 2, and a square node in 3. The function of cyclohexane tricarboxylate as a four-connected node, shown for the first time in a trigonal molecule, is in contrast to the usual role of the trimesate anion as a three-connected node in molecular complexes.

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Deposited On:29 Nov 2010 08:44
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