Synthesis and spectroscopic studies on the Schiff base ligand derived from condensation of 2-furaldehyde and 3,3'-diaminobenzidene, L and its complexes with Co(II), Ni(II), Cu(II) and Zn(II): comparative DNA binding studies of L and its Cu(II) and Zn(II) complexes

The Schiff base ligand, N,N'-bis-(2-furancarboxaldimine)-3,3'-diaminobenzidene (L) obtained by condensation of 2-furaldehyde and 3,3'-diaminobenzidene, was used to synthesize the mononuclear complexes of the type, [M(L)](NO3)2 [M=Co(II), Ni(II), Cu(II) and Zn(II)]. The newly synthesized ligand, (L) and its complexes have been characterized on the basis of the results of the elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz, FT-IR, 1H and 13C NMR, mass, UV-vis and EPR. EPR, UV-vis and magnetic moment data revealed a square planar geometry for the complexes with distortion in Cu(II) complex and conductivity data show a 1:2 electrolytic nature of the complexes. Absorption and fluorescence spectroscopic studies support that Schiff base ligand, L and its Cu(II) and Zn(II) complex exhibit significant binding to calf thymus DNA. The highest binding affinity in case of L may be due to the more open structure as compared to the metal coordinated complexes.     

Effect of solvent on absorption and fluorescence spectra of a typical fluorinated azo dye for its acidic and basic structures

The effect of 15 polar solvents on absorption and fluorescence energies of a typical fluorinated azo dye, 4-(2,3,5,6-tetrafluoro-pyridin-4-yl azo)-phenol, was reported for its acidic, MH, and basic, M, structures.For MH, the absorption energy is described on the basis of multi-linear equation with Taft's π* (solvent polarity) and β (hydrogen bond acceptor) parameters while the fluorescence energy varies rectilinearly with free energy of transferring the proton to the surrounding solvent, ΔG_t°.For M, the hydrogen bonding donor ability of protic solvent, α, is a predominant factor which affects the absorption energy while in aprotic solvents, the absorption energy correlates linearly with Kirkwood function. As the ability of the solvent for hydrogen bonding increases, the absorption band width will increase in parallel with the transition energy.     

Photoluminescence studies of iodobis-(tricyclohexylphosphine)copper(I) and iodobis-(tricyclohexylphosphine)copper(I) benzene solvate

Two newly prepared complexes were found to exhibit strong solid state emission behavior. The complexes are iodobis-(tricyclohexylphosphine)copper(I) and iodobis-(tricyclohexylphosphine)copper(I) benzene solvate. To understand the emission behavior of these complexes, density functional theory (DFT) calculations were employed. These calculations allowed the identification of major atomic contributions to HOMO, LUMO and LUMO+n orbitals. The excitation mechanism was found to be a combination of ligand to metal charge transfer (LMCT) and metal to ligand charge transfer (MLCT), with the dominance of the former. The emission lifetimes were also investigated and the decays of the complexes were found to be a bi-exponential in both methanol and cyclohexane.     

Steady-state fluorescence and photo-isomerization study of 1-methyl-4′-(p-N,N dimethyl-amino styryl) pyridinium iodide

Photochemical and thermal trans/cis isomerization reactions are reported for 1-methyl-4′-(p-N,N dimethyl-amino styryl) pyridinium iodide, Cy, which is synthesized in the trans configuration. In a basic solution the trans form, Cy_tr, cannot isomerise directly to the cis form. Its protonated form, Cy_trH⁺, is active and reacts photochemically from trans to cis isomer, Cy_cH⁺. The quantum yields Φ_tc and Φ_ct are determined in water. Deprotonation process of Cy_cH⁺ yields the cis isomer, Cy_c, which can thermally revert to the stable trans form. The rate constant and the activated parameters of the thermal reaction are also determined. Due to irreversibility of the thermal reaction , a complete molecular reaction cycle is performed in one direction. To get more information on the spectral properties of protonated form, its absorption and fluorescence spectra were investigated in sixteen neat polar protic and aprotic solvents. Absorption energy correlates linearly with hydrogen bond acceptor ability of the solvent. Another linear correlation was found between fluorescence energy of CyH⁺ and free energy for transferring the proton to the surrounding solvent, ΔG_t^o.     

Monomer-dependent synthesis of secondary amine-linked triazine-based two-dimensional polymers nanosheets

Expanding the structural diversity of crystalline two-dimensional polymers(2DPs) is highly desired but remains a considerable challenge. Herein we report the first synthesis of novel crystalline secondary amine-linked triazine-based 2DPs(SAT-2DPs) by using benzidine or 4, 4′′-diamino-p-terphenyl and cyanuric chloride under solvothermal conditions. We find the structures of diamine-based monomers play a crucial role in deciding whether the synthesized material is crystalline 2DPs nanosheets or amorphous nanoparticles, which is unexpected and provides an important understanding of the 2D polymerization mechanism.The obtained SAT-2DPs not only show a lateral size of micrometers and an ultrathin thickness of a few nanometers, but also demonstrate high crystallinity with a unique ABC stacking configuration, excellent solvent dispersibility and superior thermal stability. In addition, the resultant SAT-2DPs are used to guide uniform lithium-ion deposition due to their abundant nitrogen atoms and ordered open channels. The assembled asymmetric coin cells(Li|Cu) with SAT-2DPs realize the average coulombic efficient up to 99.3% during discharge-charge cycles. This work provides valuable insights into the synthesis of new 2DPs for various applications.     

On Lie ideals with derivations as homomorphisms and anti-homomorphisms

In [2, Theorem 3], Bell and Kappe proved that if d is a derivation of a prime ring R which acts as a homomorphism or an anti-homomorphism on a nonzero right ideal I of R, then d = 0 on R. In the present paper our objective is to extend this result to Lie ideals. The following result is proved: Let R be a 2-torsion free prime ring and U a nonzero Lie ideal of R such that u ² ∈ U, for all u ∈ U. If d is a derivation of R which acts as a homomorphism or an anti-homomorphism on U, then either d=0 or U ?Z(R).     

Effect of Mn(II) doping on crystalline perfection, nonlinear, optical and mechanical properties of KDP single crystals

The effect on crystalline perfection, second harmonic generation (SHG) efficiency, optical transparency and mechanical properties due to Mn(II) doping in KDP single crystals grown by slow evaporation solution technique by adding different quantities of MnCl₂ in the solution has been investigated. The actual incorporated quantity of Mn(II) in the crystals was evaluated by atomic absorption spectroscopy. Powder XRD study confirms the crystal system of KDP and found no additional phases at all doping levels (1 to 5 mol%). The influence of Mn(II) doping on the crystalline perfection has been assessed by high-resolution XRD and these studies revealed that the grown crystals could accommodate Mn(II) in the interstitial positions of the crystalline matrix of KDP only up to some critical concentration, above which the crystal developed structural grain boundaries. The relative SHG efficiency of the crystals was found to be increased sharply at low concentrations (1 mol%), and above this value it was decreased as the concentration increases though it is still higher than that of pure KDP. UV-Vis studies also revealed the same behavior with a significant enhancement at 1 mol% concentration and later gradually decreased. Good increment in the hardness values has been observed by increasing the doping concentrations.     

Mechanisms of loss formation in nonlinear optical crystals ZnGeP2 in the terahertz frequency range

Physical mechanisms of formation of radiation losses in the terahertz range in ZnGeP₂ crystals have been experimentally studied in the wave number range of 5–350 cm^?1 at temperatures of 10–300 K. The dominant contribution of two-phonon difference processes to the loss formation in the given frequency range has been shown.     

Synthesis, characterization of complexes of Co(II), Ni(II), Cu(II) and Zn(II) with 12-membered Schiff base tetraazamacrocyclic ligand and the study of their antimicrobial and reducing power

Schiff base tetraazamacrocyclic ligand, L (C(40)H(28)N(4)) and its complexes of types, [MLX(2)] and [CuL]X(2) (M=Co(II), Ni(II), Zn(II); X=Cl(-), NO(3)(-)) were synthesized and characterized by elemental analyses, mass, (1)H NMR, IR, UV-vis, magnetic susceptibility and molar conductance data. An octahedral geometry has been proposed for all the complexes except the copper(II) complexes which have a square planar environment. The reducing power of the Co(II) and Cu(II) complexes have been checked and compared. The ligand (L) and its complexes have also been screened against different fungi and bacteria in vitro.     

Synthesis and spectroscopic studies on complexes of N,N'-bis-(2-pyridinecarboxaldimine)-1,8-diaminonaphthalene (L); DNA binding studies on Cu(II) complex

The Schiff base ligand, N,N'-bis-(2-pyridinecarboxaldimine)-1,8-diaminonaphthalene (L), obtained by the condensation of 2-pyridinecarboxaldehyde and 1,8-diaminonaphthalene, has been used to synthesize the mononuclear complexes of the type [MLCl(2)] [M=Co(II), Ni(II), Cu(II) and Zn(II)]. The newly synthesized ligand (L) and its complexes have been characterized on the basis of results of elemental analysis, molar conductance, magnetic susceptibility measurements, Job's method and spectroscopic studies viz., FT-IR, Mass, (1)H and (13)C NMR. The UV-vis and magnetic moment data revealed an octahedral geometry around Co(II), Ni(II) and Cu(II) ions and conductivity data show a non-electrolytic nature of the complexes. Absorption and fluorescence spectroscopic studies support that Cu(II) complex exhibits significant binding to calf thymus DNA.