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 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.