Coordination self-assembly of tetranuclear Pt(ii) macrocycles with an organometallic backbone for sensing of acyclic dicarboxylic acidsElectronic supplementary information (ESI) available: Crystallographic details of 1a and 2b; IR, NMR (1H and 31P) and ESI-MS spectrum of 1, 2a-2c are available. CCDC 895738 (1a) and 895739 (2b). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2dt31828h

Coordination self-assembly of a series of tetranuclear Pt( ii ) macrocycles containing an organometallic backbone incorporating ethynyl functionality is presented. The 1 : 1 combination of a linear acceptor 1,4-bis[ trans -Pt(PEt 3 ) 2 (NO 3 )(ethynyl)]benzene ( 1 ) with three different dipyridyl donor 'clips' ( L a -L c ) afforded three [2 + 2] self-assembled Pt II 4 macrocycles ( 2a-2c ) in quantitative yields, respectively [ L a = 1,3-bis(3-pyridyl)isothalamide; L b = 1,3-bis(3-pyridyl)ethynylbenzene; L c = 1,8-bis(4-pyridyl)ethynylanthracene]. These macrocycles were characterized by multinuclear NMR ( 1 H and 31 P); ESI-MS spectroscopy and the molecular structures of 2a and 2b were established by single crystal X-ray diffraction analysis. These macrocycles ( 2a-2c ) are fluorescent in nature. The amide functionalized macrocycle 2a is used as a receptor to check the binding affinity of aliphatic acyclic dicarboxylic acids. Such binding affinity is examined using fluorescence and UV-Vis spectroscopic methods. A solution state fluorescence study showed that macrocycle 2a selectively binds ( K SV = 1.4 × 10 4 M −1 ) maleic acid by subsequent enhancement in emission intensity. Other aliphatic dicarboxylic acids such as fumaric, succinic, adipic, mesaconic and itaconic acids caused no change in the emission spectra; thereby demonstrating its potential use as a macrocyclic receptor in distinction of maleic acid from other aliphatic dicarboxylic acids. A series of Pt II 4 -metallamacrocycles has been synthesized and one of them is tested as fluorescent sensor for the discrimination of maleic acid from other acyclic dicarboxylic acids.