Dinucleating macrocyclic Schiff bases derived from thiophene and their metal complexes: the crystal structures of a free macrocycle and of a disilver complex

Abstract

Dinucleating macrocyclic Schiff bases derived from the condensation of thiophene-2,5-dicarbaldehyde and a number of a,o-alkanediamines are reported together with their barium and silver complexes.

Synthesis and Protonation Behavior of 26-Membered Oxaaza and Polyaza Macrocycles Containing Two Heteroaromatic Units of 3,5-Disubstituted Pyrazole or 1-Benzylpyrazole. A Potentiometric and1H and13C NMR Study

“…Synthesis. Heteroaromatic polyazamacrocycles containing pyridine, pyrrole, furan, and thiophene rings have been obtained following a two-step synthetic method that includes a first dipodal (2 + 2) condensation of α,ω-diamines with the corresponding dialdehydes, followed by hydrogenation of the Schiff base imine bonds. ,, However, several authors have pointed out that when such α,ω-diamines have additional NH or OH groups in the middle of the chain, the first condensation step affords a mixture of two isomers. Thus, Fenton and co-workers reported that, in the absence of metal ions, the condensation of 2,5-thiophenedicarbaldehyde with diethylenetriamine affords a solid product whose 1 H NMR spectrum corresponds to a mixture of the desired tetraimine Schiff base together with an imidazolidine isomer formed by nucleophilic addition of the two secondary amine groups of the tetraimine macrocycle across the adjacent imine bonds …”

“…Although several groups have detected the formation of imidazolidine derivatives related to IV in equilibrium with Schiff bases similar to III (X = NH), as far as we know there are few examples including X-ray structures , and a detailed NMR characterization of such compounds has not previously been reported.…”

Synthesis, complexation and antifungal, antibacterial activity studies of a new macrocyclic schiff base

“…Macrocyclic ligand was synthesized by the high dilution one-to-one [2:2] condensation of diamino compound with dicarbonyl compound in ethanol. The synthesis of macrocyclic Schiff bases using metal-free condensations of primary or diamines with dialdehydes were first published by Tasker et al [52] and Fenton et al [53]. This method has also been studied in literature .…”

Heterocyclic dialdehydes: linkers in the synthesis of macroacyclic ligands

“…By the inclusion of various heteroatoms, among them those forming part of heterocyclic fragments, in the chelate unit it is possible to vary the electronic and steric characteristics of the complexes precisely [4,5].In this work a path to the construction of new podands based on heterocyclic dialdehydes 2 and diethyl 2-[(2-aminophenyl)aminomethylidene]malonate (1) is presented. 2,5-Thiophenedicarbaldehyde (2a) and 2,6-pyridinedicarbaldehyde (2b) were used as heterocyclic dialdehydes.…”

“…By the inclusion of various heteroatoms, among them those forming part of heterocyclic fragments, in the chelate unit it is possible to vary the electronic and steric characteristics of the complexes precisely [4,5].…”