2-Hydroxyphenyl benzimidazoles and their boron complexes: synthesis, structure, aggregation-induced emission and picric acid sensing.

A series of differently substituted 2-(2-hydroxyphenyl) benzimidazoles were synthesized by a coupling reaction involving aryl dibromides and 2-hydroxyphenyl benzimidazole. These ligands react with BF·EtO to yield the corresponding boron complexes. The photophysical properties of the ligands (L1-L6) and the boron complexes (1-6) were studied in the solution state.

Push and Pull Effect of Methoxy and Nitro Groups Modifies the Spin-State Switching Temperature in Fe(III) Complexes.

We have explored the impact of electron-donating (methoxy) and electron-withdrawing (nitro) substituents on SalEen ligand based spin crossover (SCO) behavior of Fe(III) complexes. Thus, 3-X-substituted SalEen ligands were employed to prepare [Fe(3-X-SalEen)]·NCSe, where X = OMe (), H (), and NO () (3-X-SalEen is the condensation product of 3-substituted salicylaldehyde and -ethylethylenediamine). The characteristic spin transition temperature ( ) is shown to shift to a lower temperature when an electron-donating substituent (OMe) is used and to a higher temperature when an electron-withdrawing substituent (NO) is used.

Formation of supramolecular channels by reversible unwinding-rewinding of bis(indole) double helix via ion coordination.

Stimulus-responsive reversible transformation between two structural conformers is an essential process in many biological systems. An example of such a process is the conversion of amyloid-β peptide into β-sheet-rich oligomers, which leads to the accumulation of insoluble amyloid in the brain, in Alzheimer's disease. To reverse this unique structural shift and prevent amyloid accumulation, β-sheet breakers are used.

Effect of intermolecular anionic interactions on spin crossover of two triple-stranded dinuclear Fe(II) complexes showing above room temperature spin transition.

Two new Fe(II)-based dinuclear triple helicates having the formula {[Fe(L)]·(CFSO)·6.5HO·CHOH} (complex 1) and {[Fe(L)]·(ClO)·7HO·1.35CHOH} (complex 2), displaying near room temperature spin transition have been synthesized and the effect of intermolecular interactions and co-operativity between metal centers on the spin crossover (SCO) has been studied.

Fe spin crossover complexes containing NO donor ligands.

Spin crossover (SCO) is one of the most studied magnetic bistable phenomena because of its application in the field of multifunctional magnetic materials. Fe complexes in a N coordination environment have been the most well-studied in terms of their SCO behaviour. Other coordination environments, notably the NO coordination environment, has also been quite effective in inducing SCO behaviour in the corresponding Fe complexes.

Effect of Ligand Field Strength on the Spin Crossover Behaviour in 5-X-SalEen (X=Me, Br and OMe) Based Fe(III) Complexes.

The reaction of Fe(NCS) prepared in situ in MeOH with 5-X-SalEen ligands (5-X-SalEen=condensation product of 5-substituted salicylaldehyde and N-ethylethylenediamine) provided three Fe(III) complexes, [Fe(5-X-SalEen) ]NCS; X=Me (1), X=Br (2), X=OMe (3). All the complexes reveal similar structural features but a very different magnetic profile. Complex 1 shows a gradual spin crossover while complexes 2 and 3 show a sharp spin transition.

Above Room Temperature Spin Transition in Thermally Stable Mononuclear Fe(III) Complexes.

Two solvent-free mononuclear Fe(III) complexes [Fe(L)]NO (1) and [Fe(L)]ClO (2) have been synthesized by employing a new π-conjugated azo-phenyl substituted ligand, 2-(( E)-((2-(ethylamino)ethyl)imino)methyl)-4-(2-phenyldiazenyl)phenol (HL). The noncoordinated azo-phenyl part of the ligand adopts two different conformations which can exert a varied local distortion around the metal center affecting the spin crossover behavior. The magnetic data (2-450 K) reveal that complex 1 displays spin crossover above room temperature where the ligand is in linear form, while complex 2 shows an incomplete spin transition where the ligand adopts a skew form in the solid state.

3D isomorphous lanthanide coordination polymers displaying magnetic refrigeration, slow magnetic relaxation and tunable proton conduction.

Four new isostructural lanthanide-based three-dimensional (3D) coordination polymers (CPs), {[Ln(OH)(L)(HO)]·4.6HO·1.4CHCN} (Ln = Gd (1), Dy (2), Ho (3) and Er (4)), have been constructed using a sulfonate-carboxylate-based ligand (NaHL = disodium-2,2'-disulfonate-4,4'-oxydibenzoic acid) and the corresponding lanthanide metal(iii) nitrates.

Influence of the Coordination Environment on Easy-Plane Magnetic Anisotropy of Pentagonal Bipyramidal Cobalt(II) Complexes.

A rational approach of modulating the easy-plane magnetic anisotropy of mononuclear pentagonal bipyramidal Co single molecule magnets (SMMs) has been revealed in this paper. A class of three new pentagonal-bipyramidal complexes with formulas [Co(Hdaps)(MeOH)] (1), [Co(Hdaps)(NCS)(MeOH)]·(ClO)·(MeOH) (2), and [Co(Hdaps)(NCS)]·(MeOH) (3) (Hdaps = 2,6-bis(1-salicyloylhydrazonoethyl) pyridine) were studied. In these complexes, the axial positions are successively replaced by different O and N donar ligands in a systematic way.

Hamilton-Jacobi equation for the least-action/least-time dynamical path based on fast marching method.

Classical dynamics can be described with Newton's equation of motion or, totally equivalently, using the Hamilton-Jacobi equation. Here, the possibility of using the Hamilton-Jacobi equation to describe chemical reaction dynamics is explored. This requires an efficient computational approach for constructing the physically and chemically relevant solutions to the Hamilton-Jacobi equation; here we solve Hamilton-Jacobi equations on a Cartesian grid using Sethian's fast marching method.