Comprehensive studies of non-covalent interactions within four new Cu(II) supramolecules

نویسنده:
, , , , , , , , ,
سال
: 2012
چکیده: This work investigates the supramolecular aggregation of Cu(II) complexes based on a combination

of the heterocyclic N-donor ligand 2-aminopyrimidine (2-apym) and a variety of different carboxylate

ligands, like salicylic acid (H2SAL), maleic acid (H2MAL), and glycine (HGLY). Four new Cu(II)

complexes [Cu(HSAL)2(2-apym)2](I), [Cu(HSAL)2(2-apym)2]? (H2SAL)2(2-apym) (I\\'), {(H2-apym)[Cu(GLY)(m-Cl)2Cl]}n (II) and [Cu(m-MAL)(2-apym)]n (III) have been synthesized and

characterized by elemental analyses, FT-IR spectra, and X-ray structural analyses. I and I9 appear as

molecular clusters whereas II is a 1-D coordination polymer with weak axial Cu–Cl interactions.

However the last one shows a 2-D coordination polymer with trigonal bipyramidal geometry for

Cu(II) ion. The two last cases have no molecular fragments packed with non-covalent interactions. In

these new supramolecular compounds, existent species join together with the cooperation of multiple

inter/intra-molecular classical O–H…O/N, N–H…O/N, and non-classical N–H…Cl hydrogen bonds

(H-bonds), offset face to face p…p, edge to face C/N–H…p, and lp…p stacking interactions in the

form of various homo/hetero-synthons leading to architecturally different structures. DFT

calculations were used to estimate the binding energy of the involved non-covalent interactions and

whole stabilization energy of related network of I, I9, and II. Theoretical calculations facilitate the

comparison of intermolecular interactions, which demonstrate that for all of I–II, N–H…N and N–

H…O H-bonds govern the network formation. The equilibrium constants for the three proton-transfer systems including SAL/2-apym, GLY/2-apym, MAL/2-apym, the stoichiometry and stability

of complexation of these systems with Cu2+

ion in aqueous solution were investigated by

potentiometric pH titration method. The stoichiometries of the most complex species in solution was

compared to the crystalline Cu2+

ion complexes with the cited proton-transfer systems.
کلیدواژه(گان): copper,crystal engineering,proton transfer,salicylic acid (H2SAL),maleic acid (H2MAL),glycine (HGLY),2-aminopyrimidine (2-apym),binding energy,DFT
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