Crystal and molecular structures of sixteen charge-assisted hydrogen bond-mediated diisopropylammonium salts from different carboxylic acids

Cocrystallization of the commonly available organic amine, diisopropylamine, with a series of carboxylic acids gave a total of sixteen molecular salts with the compositions: diisopropylaminium 2-methyl-2-phenoxypropanate [(Hdpa)(+) center dot (mpa(-)), mpa(-) = 2-methyl-2-phenoxypropanoate] (1), diisopropylaminium 2-methyl-2-(naphthalen-2-yloxy)-propionate [(Hdpa)+ center dot (npa(-)), npa(-) = 2-methyl-2-(naphthalen-2-phenoxyloxy)-propionate] (2), diisopropylaminium indole-3-acetate [(Hdpa)(+) center dot (iaa(-)), iaa(-) = indole-3-acetate] (3), diisopropylaminium 4-chlorophenoxyacetate [(Hdpa)(+) . (cpa(-)), cpa(-) = 4-chlorophenoxyacetate] (4), diisopropylaminium 2,4-dichlorophenoxyacetate [(Hdpa)(+) center dot (dcpa(-)), dcpa(-) = 2,4-dichlorophenoxyacetate] (5), diisopropylaminium 4-hydroxybenzoate [(Hdpa)(+) center dot (hba(-)), hba(-) = 4-hydroxybenzoate] (6), diisopropylaminium 4-aminobenzoate [(Hdpa)(+) center dot (aba(-)), aba(-) = 4-aminobenzoate] (7), tetra(diisopropylaminium) tetra(1-hydroxy-2-naphthoate) trihydrate [(Hdpa)(4)(4+) center dot (2-hnpa)(4)(4-) center dot 3H(2)O, 2-hnpa = 1-hydroxy-2-naphthoate] (8), diisopropylaminium 2-hydroxy-3-naphthoate [(Hdpa)(+) center dot (3-hnpa(-)), 3-hnpa(-) = 2-hydroxy-3-naphthoatel (9), diisopropylaminium 5-bromosalicylate [(Hdpa)(+) center dot (bsa(-)), bsa(-) = 5-bromosalicylate] (10), diisopropylaminium 3,5-dinitrobenzoate [(Hdpa)(+) center dot (dna(-)), dna(-) = 3,5-dinitrobenzoate] (11), diisopropylaminium 3,5-dinitrosalicylate [(Hdpa)(+) center dot (3,5-dns(-)), 3,5-dns(-) = 3,5-dinitrosalicylate] (12), tetra(diisopropylaminium) bis(m-phthalate) monohydrate [(HdPa(+))(4) center dot (mPta2(-) center dot H2O, mpta(2-) = m-phthalate] (13), bis(diisopropylaminium) dihydrogen 1,2,3,4-butane tetracarboxylate [(HdPa(+))(2) center dot (H(2)Bta(2-)), H(2)Bta(2-) = dihydrogen 1,2,3,4-butane tetracarboxylate] (14), bis(diisopropylaminium) mucate [(Hdpa(+))(2) center dot (muc(2-)), muc(2-) = mucate] (15), and diisopropylaminium hydrogen 1,2-phenylenediacetate [(Hdpa) center dot (Hpda(-)), Hpda(-) = hydrogen 1,2-phenylenediacetate] (16). The sixteen salts have been characterised by XRD technique, IR, and elemental analysis, and the melting points of all the salts were also reported. And their structural and supramolecular aspects are fully analyzed. The result reveals that among the sixteen investigated crystals the NH groups in the diisopropylamine are protonated when the carboxylic acids are deprotonated, and the crystal packing is interpreted in terms of the strong charge-assisted N-H center dot center dot center dot O hydrogen bond formation between the ammonium and the deprotonated COOH groups. Except the N-H center dot center dot center dot O hydrogen bond; the O-H center dot center dot center dot O hydrogen bonds (charge assisted or neutral) were also found at the salts 6, 8, 9, 10, 12, 13, 14, 15, and 16. Further analysis of the crystal packing of the salts indicated that a different family of additional CH-Of CH2-O/CH3-O, CH-pi/CH3-pi, CH3-C-pi, N-pi, and pi-pi associations contribute to the stabilization and expansion of the total structures. For the coexistence of the various weak interactions these structures adopted homo or hetero supramolecular synthons or both. (C) 2017 Elsevier B.V. All rights reserved.