Crystal structure of monoaqua-(5-bromoisophthalato)-(1,2-bi(4- pyridyl)ethane)zinc(II), Zn(H₂O)(C₈H₃O₄Br)(C₁₂H₁₂N₂)

Abstract

C 20 H 17 BrN 2 O 5 Zn, triclinic, P1 (no. 2), a =8.036(5) Å, b =9.673(6) Å, c =14.549(9) Å, a =105.706(7)°, b =90.431(7)°, g =114.255(7)°, V =983.5 Å 3 , Z =2, R gt (F) =0.030, wR ref (F 2 ) =0.074, T =294 K. Source of materialThe title compound was synthesized by the reaction of 1,2-bi(4-pyridyl)ethane (bpa, 0.5 mmol), 5-bromoisophthalic acid (0.5 .mmol), Zn(OAc)2.·.4H2O(0.5 mmol) and KOH (0.5 mmol) were added to water (12 ml) in aTeflon-lined stainless steel reactor. The mixture was heated at 400 Kf or 5d ,a nd then slowly cooled down to room temperature. Colourless crystals of the title compound were obtained. DiscussionDesign of the solid state with molecules that encode well defined noncovalent motifs has recently become arapidly growing area of research due to the fascinating molecular and/or supramolecular structural diversity [1,2] and potential applications for catalysis [3,4] and material sciences [5,6]. Asuccessful strategy in building such networks is to employ appropriate bridging ligands that can bind metal ions in different modes and provide apossible way to achieve more robust polymeric structures [7,8]. In this context, benzenedicarboxylic acid and its derivatives, such as 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 5-hydroxyisophthalic acid are widely used as building blocks to link metal ions to produce metal-organic frameworks with interesting structures and properties [9]. Recently, benzenedicarboxylic acid, providing specific rigid molecules, seized our attention for constructing various coordination polymer. The interesting results inspired us to investigate its analogues, 2-bromo-1,4-benzenedicarboxylic acid, for the following reasons: (a) it has two carboxyl groups which may be completely or partially deprotonated, inducing rich coordination modes and allowing interesting structures with higher dimensions; (b) it can act not only as hydrogen-bond acceptor but also as hydrogen-bond donor, depending upon the numbers of deprotonated carboxyl groups. In the title crystal structure, the asymmetric unit consists of one zinc(II) ion, one bpa molecule, one 5-bromoisophthalate anion, and one coordinated water molecule. The zinc(II) ion has adistorted trigonal-bipyramidal arrangement (ZnO 4N) with four oxygen atoms from three 5-bromoisophthalate anions and one water molecule, and one nitrogen atom from one bpa molecule. The Zn-Nb ond lengths are both 2.029(3) Å and the Zn-Ob ond lengths are in the range of 1.943(2) -2 .823(3) Å,r espectively. The bpa molecule adopts an unidentate coordination mode and the unligated N2 atom acts as the hydrogen-bonding acceptor.The 5-bromoisophthalate anion shows m 3 -bridging coordination mode, which link the zinc(II) ions into 1D ladder-like framework.The 5-bromoisophthalate anion, bpa molecule and water molecule are involved in intramolecular O-H···O, and O-H···Nhydro-gen bonds, which result in a3Dsupramolecular structure.

Significant Positional Isomeric Effect on Structural Assemblies of Zn(II) and Cd(II) Coordination Polymers Based on Bromoisophthalic Acids and Various Dipyridyl-Type Coligands

“…The adjacent 2D networks are parallel and arranged in an ABAB stacking sequence (see Figure b). This structure has been reported recently …”