Oxamidato-bridged Re(I)-based supramolecular rectangles with an ester functionality have been synthesized via an orthogonal bonding approach under solvothermal conditions. Self-assembly of Re2(CO)10 and oxamide ligands (H2L1 = N,N′-dibutyloxamide, H2L2 = N,N′-dioctyloxamide, H2L3 = N,N′-didodecyloxamide, and H2L4 = N,N′-dibenzyloxamide) with the pyridyl ligand phenyl-1,4-bis(isonicotinate) (pbin) has resulted in the formation of metallarectangles of general formula [{(CO)3Re(μ-η4-L)Re(CO)3}2(μ-pbin)2] (1–4), wherein L = N,N′-dibutyloxamidato (1), N,N′-dioctyloxamidato (2), N,N′-didodecyloxamidato (3), N,N′-dibenzyloxamidato (4) and pbin = phenyl-1,4-bis(isonicotinate). The metallarectangles have been characterized using spectroscopic techniques, and single-crystal X-ray structures have been obtained for 1 and 4. The guest binding ability of 2 has been investigated with a few aromatic amines and an amino ketone using electronic absorption and fluorescence emission spectroscopy, and the results revealed a strong binding interaction between host–guest species. The luminescence properties of 2 and 3 have been tuned using organic–aqueous solvent mixtures.

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Oxamidato-bridged Re(I)-based hexanuclear trigonal prisms with ester functionality have been synthesised via a multicomponent self-assembly process under solvothermal conditions. The self-assembly of Re2(CO)10, oxamide ligands (H2L1 = N,N′-dibutyloxamide, H2L2 = N,N′-dioctyloxamide, H2L3 = N,N′-didodecyloxamide and H2L4 = N,N′-dibenzyloxamide) and phenyl-1,3,5-tris(isonicotinate) (ptin) resulted in the formation of metallaprisms with the general formula [{(CO)3Re(μ–η(4)-L)Re(CO)3}3(μ3-ptin)2] (1–4). The metallaprisms 1–4 have been characterised using spectroscopic techniques, and the molecular structure of 4 has been elucidated by single-crystal X-ray diffraction methods. Investigations on the guest binding ability of 2 with a few aromatic alcohols and L-tryptophan using UV–vis and fluorescence spectroscopic titration experiments revealed strong host–guest interactions. The luminescence enhancement studies of 2 and 3 have been carried out using organic-aqueous solvent mixtures.

Multicomponent self-assembly of Re 2 (CO) 10 , diaryl dichalcogenide ligands (REER), and phenyl-1,3,5-tris(isonicotinate) (ptin) under solvothermal conditions has resulted in the formation of chalcogen-bridged trigonal metallaprisms of the general formula [{(CO) 3 Re(μ-ER) 2 Re(CO) 3 } 3 (μ 3 -ptin) 2 ] (1−5), wherein E = S, Se and R = phenyl, ptolyl, benzyl. Oxidative addition of diaryl disulfide/diaryl diselenide to Re 2 (CO) 10 with the ester-functionalized tritopic linker ptin has yielded trigonal metallaprisms 1−5 under facile reaction conditions. The metallaprisms 1−5 have been characterized using elemental analysis and IR, UV−vis, and NMR spectroscopic techniques. Single-crystal X-ray structures have been obtained for 3 and 4. The structural features and chirality of metallaprisms 3 and 4 in the solid state have been highlighted. ■ INTRODUCTIONProgrammed self-assembly of metal precursors and organic ligands encoded with information required for recognition has led to the generation of an extensive range of two-dimensional and three-dimensional discrete metallasupramolecular architectures. 1−4 An explicit advantage in coordination-driven selfassembly is the tunability of size, shape, and properties of supramolecules by the logical choice of complementary building blocks with interesting geometries and functional groups. Several pioneers in the field have exploited this advantage to develop intriguing metallacycles and metallacages that are useful in various fields of science and technology. 5−7 An overview of the literature in the past two decades reveals that self-assembly processes between two sophistically designed building components (one acceptor and one donor) have been well established, whereas self-assembly involving more than two components (one acceptor and two different donors/one donor and two different acceptors) have been much less documented, perhaps due to a number of probable reaction pathways leading to a mixture of species. 8 A judicious choice of building blocks implementing selective recognition to form a single discrete product from a multicomponent mixture remains a challenging task. 9 Fujita and co-workers have reported trigonal-prismatic cages of M 6 L 2 L′ 3 type, using Pd metal hinges, linear ditopic organic pillars, and planar tritopic ligands, by multicomponent self-assembly in the presence of templates. 10 Recently, Stang et al. have reported the templatefree, selective formation of a trigonal prism from a mixture of 90°Pt(II) acceptor, a carboxylate ligand, and an exotridentate pyridyl ligand. The formation of this trigonal prism was facilitated by the charge separation effect favoring the heteroleptic coordination motif with Pt(II) centers. 11 Lees and Sun have reported the one-step self-assembly of a hexarhenium prism from Re(CO) 5 (OTf), 2,2′-bipyrimidine, and 2,4,6-tripyridin-4-yl-1,3,5-triazine (4-tpt) in a 6:3:2 ratio. 8c A few more hexarhenium trigonal prisms have been reported by Hupp, Lu, and other research groups by either a stepwise process or one-step synthesis. 12...