Coordination polymers with 4′-(4-(anthracen-9-yl)phenyl)- and 4′-(4-(naphthalen-1-yl)phenyl)-4,2′:6′,4"-terpyridines: Mono-, di- and heptazinc(II) nodes

Reactions of 4'-(4-(anthracen-9-yl)phenyl)-4,2':6',4 ''-terpyridine (2) with zinc(II) acetate lead to helical one-dimensional polymers [{Zn(OAc)(2)(2)}(n)] which crystallize either as racemates or the homochiral polymer containing mononuclear {Zn(OAc)(2)} nodes linked by divergent 4,2':6',4 ''-terpyridine ligands. In contrast, when 4'-(4-(naphthalen-1-yl)phenyl)-4,2':6',4 ''-terpyridine (3) reacts with zinc(II) acetate, a one-dimensional coordination polymer [{Zn-2(mu-OAc)(4)(3)}(n)] in which the metal nodes are dinuclear {Zn-2(mu-OAc)(4)} units is formed. This mimics the assembly formed when the ligand is 4'-(4-biphenylyl)-4,2':6',4 ''-terpyridine (1). In addition, crystals of [{Zn-7(mu-OAc)(10)(mu(4)-O)(2)(3)}(n)] were isolated and structural determination reveals a one-dimensional coordination polymer in which each ligand 3 bridges between {Zn-7(mu-OAc)(10)(mu(4)-O)(2)} clusters. Ligands 2 and 3 are both emissive in solution and in the solid state. The emission spectra of ethanol solutions of [{Zn(OAc)(2)(2)}(n)] and [{Zn-2(mu-OAc)(4)(3)}(n)] are consistent with dissociation of the complexes, the emission maxima mimicking those of the free ligands. The emission of 2 in the solid state is essentially quenched upon complexation with zinc(II) acetate, whereas on going from 3 to [{Zn-2(mu-OAc)(4)(3)}(n)], a red-shift is observed (416 to 434 nm) without change in the quantum yield (ca. 1.6%). (c) 2013 Elsevier Ltd. All rights reserved.