ZIGZAG METAL-ORGANIC POLYMER: (2,2’-DIPYRIDYLAMINE)(TEREPHTALATO)ZINC(II) HYDRATE

Abstract

Anions of terephthalic (1,4-benzenedicarboxylic) acid, tpht2–, act as a potential polydentate and bridging ligands in metal-organic framework structures. COO groups are usually coordinated either in mono-, bi- or polydentate ways, while the simultaneous presence of two differently coordinated tpht ions is very uncommon [1]. As a continuation of our previous studies [2], the title complex has been hydrothermally synthesized and characterized by single crystal X-ray diffraction, elemental and TG/DSC analysis and FT-IR spectroscopy. The structure (Fig. 1) consists of [Zn(dipya)(tpht)] complex units (dipya is 2,2’-dipyridylamine) and one solvent water molecule. There are two independent tphts: one tpht is coordinated as bis-monodentate and another as bis-chelate ligand. In this way, zigzag polymeric chains are formed (Fig. 2). The coordination geometry around Zn(II) atom can be described as deformed square pyramid. The water molecule is triply hydrogen bonded connecting even three adjacent chains and leading to the formation of 3D framework structure. Further stabilization of the structure occurs through edge-to-face C–H…π interactions among H atom from bis-monodentate tpht in one chain and aromatic ring from bis-chelate tpht in neighboring chain (H···Cg distance 2.892 Å). Crystal data: C72H60Zn4N12O20, Mr = 1674.8, monoclinic, space group P21/n, a = 9.875(2), b = 14.371(3), c = 12.264(3) Å, β = 95.87(3) o , V = 1731.3(6) Å3 , Z = 1, F(000) = 856, ρx = 1.606 g cm–3, μ (MoKα) = 1.455 mm–1. The refinement on F 2 (264 parameters) yielded R1 = 0.0478, wR2 = 0.0704, S = 1.043 for all data, and R1 = 0.0345 for 2604 observed reflections with I ≥ 2σ(I).

U metal-organskim umreženim strukturama anjoni tereftalne (1,4-benzendikarboksilne) kiseline, tpht2–, predstavljaju potencijalne polidentatne i mostovne ligande. COO– -grupe su najčešće koordinirane na mono-, bi- ili polidentatni način, dok je istovremeno prisustvo dva različito koordinirana tpht-jona veoma retko [1]. Kao nastavak naših ranijih istraživanja [2], hidrotermalnom sintezom dobijen je navedeni kompleks i okarakterisan rendgenskom strukturnom, elementarnom i TG/DSC analizom i IC-spektroskopijom. Struktura (sl. 1) se sastoji od [Zn(dipya)(tpht)] kompleksnih jedinki (dipya je 2,2’-dipiridilamin) i nekoordiniranog molekula vode. Postoje dva nezavisna tpht liganda: jedan je koordiniran kao bis-monodentatni, a drugi kao bis-helatni ligand. Na taj način se formiraju cik-cak polimerni lanci (sl. 2). Geometrija oko atoma Zn(II) može se opisati kao deformisana kvadratna piramida. Molekul vode gradi tri vodonične veze povezujući čak tri susedna lanca i formirajući 3D strukturu. Dalja stabilizacija strukture odvija se pomoću „edge-to-face” C–H...π interakcija između H-atoma bis-monodentatnog tpht u jednom lancu i aromatičnog prstena bis-helatnog tpht u susednom lancu (H···Cg rastojanje iznosi 2,892 Å). Kristalografski podaci: C72H60Zn4N12O20, Mr = 1674,8, monoklinični sistem, prostorna grupa P21/n, a = 9,875(2), b = 14,371(3), c = 12,264(3) Å, β = 95,87(3) o , V = 1731,3(6) Å3 , Z = 1, F(000) = 856, ρx = 1,606 g cm–3, μ (MoKα) = 1,455 mm–1. Utačnjavanje sa F 2 (264 parametara) dalo je R1 = 0,0478, wR2 = 0,0704, S = 1,043 za sve podatke, i R1 = 0,0345 za 2604 refleksija sa I ≥ 2σ(I).