Role of incorporated SCN− or SO42− in organically templated chlorocadmates: synthesis, structural characterization and photoluminescence property.

Based on an aim of introducing the SCN − or SO 4 2 − group into the organically templated chlorocadmates, a series of room-temperature reactions at pH 2 were performed, creating four new Cd(II) hybrids as [L1] 4 [Cd 4 Cl 6 (SCN) 10 (H 2 O) 2 ] (L1 = 1,1′-dibenzyl-4,4′-bipyridium) 1 , [H 4 L2][CdCl 4 (SCN) 2 ] (L2 = 1,4-bis(4-pyridylmethyl)piperazine) 2 , [HL3] 3 [CdCl 3 ]SO 4 (L3 = 2-amino-6-chloropyridine) 3 , and [HL4] 3 [CdCl 3 ]SO 4 (L4 = 2-amino-6-bromopyridine) 4 . X-ray single-crystal diffraction analysis reveals that (i) templated by L1 2+ , 1 shows a 1-D single-chain structure, which is based on the dinuclear [Cd 2 Cl 3 (SCN) 4 (H 2 O)] 3 − clusters by the μ-1,3-mode SCN − groups; (ii) templated by H 4 L2 4+ , 2 only exhibits a mononuclear structure. However, via the intermolecular weak N pyridine H⋯Cl, N piperazine H⋯Cl and S SCN ⋯S SCN interactions, 2 self-assembles into a 3-D supramolecular network with a (4,6)-connected topology; (iii) 3 and 4 possess the similar structures. Via the N pyridine/amino H⋯O and π⋯π interactions, the introduced SO 4 2 − groups and the organic base molecules aggregate together into a 3-D supramolecular network with the 1-D channels. Within the channel, the Cl − ions triplely bridge the Cd 2+ centers into a 1-D linear [CdCl 3 ] − chain. Based on the structural information and the previous related reports, the role of the introduced SCN − or SO 4 2− group in the hybrid is revealed. SCN − acts as two roles: (i) a linker; (ii) a cutter. Sometimes SO 4 2− serves as a linker, while sometimes SO 4 2− connects with organic base into a supramolecular aggregation, acting as a new templating agent. The photoluminescence analysis reveals that 2 , 3 and 4 emit light with the maxima at 535 nm for 2 ( λ ex = 465 nm), 462 nm for 3 ( λ ex = 428 nm), and 465 nm for 4 ( λ ex = 430 nm), respectively. In particular, the emissions for all are strong, and can be seen under the ultraviolet (UV) lamp. [ABSTRACT FROM AUTHOR]