Synthesis and Spectroscopic and Structural Characterization of Oxamidato-Bridged Rhenium(I) Supramolecular Rectangles with Ester Functionalization

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 Re-2(CO)(10) and oxamide ligands (H(2)L1 = N,N'-dibutyloxamide, H(2)L2 = N,N'-dioctyloxamide, H(2)L3 = N,N'-didodecyloxamide, and H(2)L4 = N,N'-dibenzyloxamide) with the pyridyl ligand phenyl-1,4-bis(isonicotinate) (pbin) has resulted in the formation of metallarectangles of general formula [{(CO)(3)Re(mu-eta(4)-L)Re(CO)(3)}(2)(mu-pbin)(2)] (1-4), wherein L = N,N'-dibutyloxamidato (1), N,N'-dioctyloxarnidato (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.