Reaction of ?-alkoxyacroleins with semicarbazide and its S-, Se-, and NH-analogs

Keiko, N. A.; Mamashvili, T. N.; Rassolova, G. V.; Kashik, T. V.; Kalikhman, I. D.; Vbronkov, M. G.

doi:10.1007/bf00995696

Cited by 1 publication

(2 citation statements)

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“…Ligands. The synthetic route (Scheme 1) employed here for the bis(selenosemicarbazone) ligands 1a-c gave higher yields than that previously reported for 1b 28 but also gave traces of dark precipitate of selenium. This is typical of selenosemicarbazides 29 and was minimized by performing the reaction quickly.…”

Section: Resultsmentioning

confidence: 63%

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Hypoxia-Targeting Copper Bis(selenosemicarbazone) Complexes: Comparison with Their Sulfur Analogues

et al. 2003

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The first copper bis(selenosemicarbazone) complexes have been synthesized, using the ligands glyoxal bis(selenosemicarbazone), pyruvaldehyde bis(selenosemicarbazone), and 2,3-butanedione bis(selenosemicarbazone). Their spectroscopic properties indicate that they are structurally analogous to their well-known square-planar sulfur-containing counterparts, the copper bis(thiosemicarbazone) complexes. Spectroscopic comparison of the sulfur- and selenium-containing complexes provides insight into their electronic structure. The effects on spectroscopic and redox properties of replacing sulfur with selenium, and of successive addition of methyl groups to the ligand backbone, are rationalized in terms of their electronic structure using spin-unrestricted density functional calculations. These suggest that, like the sulfur analogues, the complexes have a very low-lying empty ligand-based pi-orbital immediately above the LUMO, while the LUMO itself has d(x2)-(y2) character (i.e., is the spin partner of the HOMO). Replacement of S by Se shifts the oxidation potentials much more than the reduction potentials, whereas alkylation of the ligand backbone shifts the reduction potentials more than the oxidation potentials. This suggests that oxidation and reduction involve spatially different orbitals, with the additional electron in the reduced species occupying the ligand-based pi-orbital rather than d(x2)-(y2). Density functional calculations on the putative singlet Cu(I)-reduced species suggest that this ligand pi-character could be brought about by distortion away from planarity during reduction, allowing the low-lying ligand pi-LUMO to mix into the d(x2)-(y2)-based HOMO. The analogy in the structure and reduction behavior between the sulfur- and selenium-containing complexes suggests that labeled with positron emitting isotopes of copper (Cu-60, Cu-62, Cu-64), the complexes warrant biological evaluation as radiopharmaceuticals for imaging of tissue perfusion and hypoxia.

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Section: Resultsmentioning

confidence: 63%

“…Here we report the first selenium-containing analogues of these complexes. Monoselenosemicarbazone complexes have previously been evaluated for pharmacological uses − but no metal complexes of bis(selenosemicarbazone) ligands are known, and only one bis(selenosemicarbazone) ligand, 1b , has been previously reported …”

Section: Introductionmentioning

confidence: 99%