Schiff Base and Reduced Schiff Base Ligands

Abstract

Supramolecular chemistry of Schiff base ligands and their reduced homologues is rapidly growing and gaining increased attention due to their convenient and straightforward synthetic methods and a wide range of complexation modes with almost all types of metal ions. In fact, the phenomenon of molecular recognition, self‐organization and self‐assembly, and host–guest chemistry through covalent and noncovalent interactions is pivotal to the understanding and development of supramolecular chemistry. In this direction, several forms of acyclic and macrocyclic Schiff bases and their reduced forms are employed to gain more insights and correctly ascertain the effect of different donor atoms, their relative position, the number and size of the chelating rings formed, the flexibility, and the geometry around the coordinating moiety on the molecular recognition process and selective binding of cations, anions, and/or neutral species. In this connection, this chapter deals with the supramolecular and molecular recognition properties and interesting host–guest complexes and metalla–supramolecular network structures derived from several acyclic and cyclic Schiff bases and reduced Schiff base ligands. Various solid‐state metalla‐supramolecular network structures are delineated ranging from hydrogen‐bonded linear polymers and helical coordination polymers, and 2D sheets to 3D network architectures constructed via N H⋯O, C O⋯H O solvent , O H⋯O, N H⋯O C, hydrogen bonds and C O⋯π, C H⋯π, and π–π stacking interactions. This review gives an account of the observed structural diversity in relation to the role of different donors and acceptors, aqua ligands and solvents, nature of the ligands and metal ions, and the coordination geometry around the metal ions.

Applications of Cucurbiturils in Medicinal Chemistry and Chemical Biology

“…One of the major challenges in modern-day pharmacology and medicine is the stable formulation and targeted delivery of therapeutics (Ghosh and Nau, 2012; Sreenivasolu, 2012; Sanku et al, 2019). A major effort in pharmaceutical research is being invested with the aim to achieve the highest impact of a particular therapeutic agent or drug on living systems by creating appropriate delivery vehicles that affect, on one hand, delivery at the desired target and that protect, on the other hand, drug molecules from degradation.…”

Nano‐Zn[2‐boromophenylsalicylaldiminemethylpyranopyrazole]Cl2 as a novel nanostructured Schiff base complex and catalyst for the synthesis of pyrano[2,3‐d]pyrimidinedione derivatives

“…Schiff bases are prepared by the reaction of a primary amine with an aldehyde or a ketone. Schiff base compounds are widely studied and applied as one of the significant classes of ligands due to the easy and convenient protocols for their preparation and their interesting coordination chemistry . A Schiff base ligand as an imine or azomethine compound can be used to produce a Schiff base complex by metal–ligand coordination.…”

Synthesis of 4‐((2‐hydroxynaphthalen‐1‐yl)(aryl)methyl)‐5‐methyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐ones using nano‐Zn‐[2‐boromophenyl‐salicylaldimine‐methylpyranopyrazole]Cl2 nanoparticles

“…Schiff base compounds are widely introduced as one of the important groups of ligands because of their easy and convenient protocols for the synthesis and their interesting coordination chemistry . Lately, we have prepared and identified a new category of Schiff base complexes by the reaction of pyranopyrazole derivatives with salicylaldehyde and different metal salts .…”