Krapa Shankar

Organic cations controlling the nuclearity of copper(II) 2,5-pyridinedicarboxylates

Depending on the organo-cation mononuclear or polynuclear copper(II) 2,5-pyridinedicarboxylates (L) are formed. Mononuclear complexes with [ML2(H2O)] anions are formed when the cations are derived from ethylenediamine (en), N,N,N′,N′-tetramethylethylenediamine (tmen), 1,5-diaminopentane (dap) and 1,4-diazabicyclo[2.2.2]octane (dabco). The use of 4-amino-benzylamine (4aba) as the cation source leads to the hexa-coordinated mononuclear complex [CuL2(H4aba)2]·8H2O. The use of 1,8-diaminooctane (dao) results in a trinuclear complex with the [Cu3L6]6− anion. The trinuclear anion has copper ions in a square pyramidal and square planar geometry. The use of diethylenetetramine (deta) led to a coordination polymer which had unique hexa and penta coordinated copper ions. It is comprised of dinuclear copper 2,5-pyridinedicarboxylates bridged by mononuclear [ML2]2− units through side on contacts between the carbonyls on the dinuclear part. The 8-aminoquinolinium cations act as counter ions of the coordination polymer with [CuL2]2− repeat units. In this coordination polymer, the cations are π-stacked in one dimension. The variation in coordination numbers and the types of chains in the coordination polymers are described.

Different carboxylic acid homodimers in self-assemblies of adducts of 3-carboxyphenoxyacetic acid with nitrogen containing compounds

AbstractDifferent hydrogen bonded dimeric motifs of 3-carboxyphenoxyacetic acid (H2cpa) observed in the self-assemblies of salts or cocrystals of H2cpa with nitrogen containing compounds are discussed. Pyridinium salt of the H2cpa is a self-assembly of Hcpa with the pyridinium cation. The assembly is a combination of sub-assemblies of two Hcp anions with two pyridinium cations, in which the Hcpa cations are interconnected through carboxylate-carboxylic acid interactions. The cocrystals of H2cpa with isoquinoline or isonicotinamide are self-assemblies of hydrogen bonded dimers of H2cpa holding the respective guest molecule. However, the dimeric assemblies of H2cpa in these two cases are different from each other; the former cocrystal has carbony-hydroxyl type interactions in it whereas the latter cocrystal has unconventional dimeric sub-assemblies of H2cpa with hydroxyl-hydroxyl type hydrogen bond interactions. The cocrystal of H2cpa with theophylline has sub-assemblies of two H2cpa molecules interacting with two theophylline guest molecules, where the theophylline molecules are hydrogen bonded in two different ways. Graphical AbstractEffects of guest molecules to stabilize dimeric motifs of 3-carboxyphenoxyacetic acid possessing different carbonyl-hydroxyl and hydroxyl-hydroxyl interactions are described.

CCDC 1531219: Experimental Crystal Structure Determination

Related Article: Krapa Shankar, Munendra Pal Singh, Jubaraj B. Baruah|2017|Inorg.Chim.Acta|469|440|doi:10.1016/j.ica.2017.09.055