Self-Assembly of Molecular Prisms via Pt3 Organometallic Acceptors and a Pt2 Organometallic Clip

Abstract

The design and two-component [2 + 3] self-assembly of a series of new organometallic molecular prisms (3a−d) are described. Assemblies 3a,b incorporate 4,4′,4′-tris[ethynyl-trans-Pt(PEt3)2(NO3)]triphenylamine (1a) containing a Pt-ethynyl functionality as tritopic planar acceptor and organic “clips” 2a and 2b, respectively [where 2a = 1,3-bis(3-pyridyl)isophthalic amide; 2b = 1,3-bis(ethynyl-3-pyridyl)benzene]. In a complementary approach an organic tritopic planar donor ligand 2c [2c = 4,4′,4′-tris(4-pyridylethynyl)triphenylamine] was assembled with an organometallic “clip”, 1,8-bis[{trans-Pt(PEt3)2(NO3)}ethynyl]anthracene (1b), to obtain prism 3c. A new organometallic carbon-centered acceptor, 1,1,1-tris[4-{trans-Pt(PEt3)2(NO3)}ethynylphenyl]ethane (1c), has been prepared, and its prism derivative (3d) using an organic “clip” is prepared. Assemblies (3a−d) were characterized by multinuclear NMR spectroscopy, electrospray ionization mass spectroscopy, and elemental analysis. 3a−d showed fluorescence behavior in solution, and quenching of fluorescence intensity (3a, 3c−d) was noticed upon addition of TNT (2,4,6-trinitrotoluene), a common constituent of many commercial explosives. A thin film of the assembly 3d made by spin coating of a solution of 3 × 10−5 M in DMF on a 1 cm2 quartz plate showed fluorescence response to the vapor of TNT.