One-pot synthesis of oxamidato-bridged hexarhenium trigonal prisms adorned with ester functionality

Abstract

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.

Self‐Assembly of Oxamidato‐Chelated ReI‐ and MnI‐Based Flexible Dinuclear Horse‐Stirrup‐Like Metallacycles

“…[45,46] The M···M nonbonding distances of the butyloxamidato-bridged dinuclear metallacycles are slightly longer than those of their benzyloxamidato-bridged analogues. The average Mn-CO bond lengths of 2 and 3 are 1.801 and 1.800 Å, whereas the Re-CO bond lengths of 5 and 6 are 1.909 and 1.901 Å, respectively.…”

“…[32,[40][41][42][43][44][45][46] Further, a strong band in the range ν = 1596-1604 cm -1 was characteristic of the C=O stretching frequency of the bridging oxamide moiety. The shift of the oxamide C=O stretching frequency and the disappearance of the NH stretching frequency in comparison with the spectra of the free oxamide ligands indicated the chelation of the oxamide ligands between the two metal centers.…”

“…In 1-6, two diastereotopic methylene protons adjacent to the nitrogen atom of the oxamidato bridge appeared as two doublets in the region δ = 5.33-3.13 ppm. [45,46] The aliphatic protons of bpe and bpp appeared as multiplets in the range δ = 3.47-2.27 ppm. The H 2 -H 4 protons of the butyloxamidato group appeared at δ = 1.80-0.97 ppm.…”

“…Similarly, the rhenium analogues 4-6 displayed two higher-energy absorption bands at λ max = 228 and 266 nm for ligand-centered transitions, and the lowerenergy bands at λ max = 309-316 nm were due to MLCT transitions. [28,29,46] On excitation of the MLCT region, 1 displayed multiple broad emissions between λ max = 404 and 460 nm. On the other hand, the rhenium-based 4 exhibited two emissions at λ max = 392 and 508 nm on excitation at 317 nm, whereas 5 and 6 displayed multiple emissions in the range λ max = 406-458 nm.…”

Rhenium‐Carbonyl‐Based Supramolecular Coordination Complexes: Synthesis, Structure and Properties

“…Manimaran and coworkers continued with the strategy of incorporation of ester functionality onto the cavity walls of the metallacycles and synthesized rhenium‐based trigonal prism 9 . The incorporation of ester groups provided additional functional arms to interact with the guest molecules rendering these as host for aromatic alcohols such as catechol, resorcinol and phloroglucinol.…”