Ni(II) and Zn(II) Complexes Containing Alkynyl Functionalized Salicylaldimine Ligand and Heterocyclic Coligand: Synthesis,Characterization and Luminescence Properties

Some nickel(II) and zinc(II) complexes of the type [Ni(L)(phen/bipy)]X (1a–6a) and [Zn(L) (phen/bipy)]X (1b–6b) (where L = 2-{(E)-[(4-trimethylsilylethynylphenyl)imino]methyl}-4-(4-nitro phenylethynyl)phenol; phen = 1, 10-phenanthroline, bipy = 2, 2´-bipyridine; X = ClO₄ ^?, BF₄ ^?, PF₆ ^?) have been prepared and characterized on the basis of elemental analyses, FTIR, ¹H NMR and mass spectral studies. The molecular structure of L was determined by single crystal X-ray diffraction studies. The electrochemical behaviour of the Ni(II) complexes indicate that the phen complexes appears at more positive potential as compared to those for bipy complexes, as a consequence of its strong π-acidic character. TGA was carried out to study the thermal behavior of the complexes. Room temperature luminescence is observed for all complexes corresponds to π → π* ILCT transition. The size of the counter anion and heterocyclic coligands phen and bipy shows marked effect on emission properties of the complexes.     

Copper(I) Complexes of N-(2-{[(2E)-2-(4-Nitrobenzylidenyl)Hydrazinyl]Carbonyl}Phenyl)Benzamide and Triphenylphosphine: Synthesis,Characterization and Luminescence Properties

Copper(I) complexes of the formula [Cu(L)(PPh₃)₂]X (1–4) (X = Cl(1), ClO₄(2), BF₄(3) and PF₆(4)) [where L = N-(2-{[(2E)-2-(4-nitrobenzylidenyl)hydrazinyl]carbonyl}phenyl)benzamide; PPh₃ = triphenylphosphine] have been prepared by the condensation of N-[2-(hydrazinocarbonyl)phenyl]benzamide with 4-nitrobenzaldehyde followed by the reaction with CuCl, [Cu(MeCN)₄]ClO₄, [Cu(MeCN)₄]BF₄ and [Cu(MeCN)₄]PF₆ in presence of triphenylphosphine as a coligand. Complexes 1–4 were then characterized by elemental analyses, FTIR, UV-visible and ¹H NMR spectroscopy. Mononuclear copper(I) complexes 1–4 were formed with L in its keto form by involvement of azomethine nitrogen and the carbonyl oxygen along with two PPh₃ groups. A single crystal X-ray diffraction study of the representative complex [(Cu(L)(PPh₃)₂]CIO₄ (2) reveals a distorted tetrahedral geometry around Cu(I). Crystal data of (2): space group = C2/c, a = 42.8596 (9) Å, b = 14.6207 (3) Å, c = 36.4643 (7) Å, V = 20,653.7 (7) ų, Z = 16. Complexes 1–4 exhibit quasireversible redox behaviour corresponding to a Cu(I)/Cu(II) couple. All complexes show blue-green emission as a result of fluorescence from an intra-ligand charge transition (ILCT), ligand to ligand charge transfer transition (LLCT) or mixture of both. Significant increase in size of the counter anion shows marked effect on quantum efficiency and lifetime of the complexes in solution.     

Orange Fluorescent Ru(III) Complexes Based on 4′-Aryl Substituted 2,2′:6′,2″-Terpyridine for OLEDs Application

A series of ruthenium (III) complexes of the formulae [Ru(4-Mephtpy)₂]Cl₃(1) [Ru(L ₁ )], [Ru(3,4,5-tmphtpy)₂]Cl₃(2) [Ru(L ₂ )], and [Ru(4-thptpy)₂]Cl₃(3) [Ru(L ₃ )], (where L?=?terpy?=?2.2′:6′2″ terpyridine ligands) are synthesized. The complexes were characterized by elemental analyses, spectroscopic and electrochemical data. The density functional theory (DFT) outlines the geometric optimisation and electronic charge transition of these complexes. Photophysical studies describe that the luminescence of Ru(III) complexes is due to electronic transition between the energy levels of singly unoccupied molecular orbitals (SUMO) and singly occupied molecular orbitals (SOMO). It also exhibits the potential charge transfer to π–π* and n–π* states due to MLCT and ILCT processes of the complexes. The observed bands centered at 591 and 620 nm demonstrate that these emissions originated from the transition of SUMO to SOMO energy levels, that is, from the radiative decay from the doublet exciton. Due to the heavy metal effect of Ru(III) ions the photophysical behaviour depends on the MLCT process. In conclusion, that the all three Ru(L ₁ -L ₃ ) complexes are fallen orange emission.     

Spectroscopic,Computational, Antimicrobial,DNA Interaction,In Vitro Anticancer and Molecular Docking Properties of Biochemically Active Cu(II) and Zn(II) Complexes of Pyrimidine-Ligand

Biochemically active Cu(II) and Zn(II) complexes [CuL(ClO₄)₂(1) and ZnL(ClO₄)₂(2)] have been synthesized from N,N donor Schiff base ligand L derived from4,6-dichloropyrimdine-5-carboxaldehyde with 4-(2-aminoethyl)morpholine. The L, complexes 1 and 2 have been structurally characterized by elemental analysis, ¹H-NMR, FTIR, MS, UV-Visible and ESR techniques. The results obtained from the spectral studies supports the complexes 1 and 2 are coordinated with L through square planar geometry. DFT calculations results supports, the ligand to metal charge transfer mechanism can occur between L and metal(II) ions. The antimicrobial efficacy results have been recommended that, complexes 1 and 2 are good anti-pathogenic agents than ligand L. The interaction of complexes 1 and 2 with calf thymus (CT) DNA has been studied by electronic absorption, viscometric, fluorometric and cyclic voltammetric measurements. The calculated K_b values for L, complexes 1 and 2 found from absorption titrations was 4.45?×?10⁴, L; 1.92?×?10⁵, 1 and 1.65?×?10⁵, 2. The Ksv values were found to be 3.0?×?10³, 3.68?×?10³and 3.52?×?10³ for L, complexes 1 and 2 by using competitive binding with ethidium bromide (EB). These results suggest that, the compounds are interacted with DNA may be electrostatic binding. The molecular docking studies have been carried out to confirm the interaction of compounds with DNA. Consequently, in vitro anticancer activities of L, complexes 1 and 2 against selected cancer (lung cancer A549, liver cancer HepG2 and cervical carcinoma HeLa) and normal (NHDF) cell lines were assessed by MTT assay.     

2,4,6-Triazido-1,3,5-Triazine, 2,4,6-Triazidopyrimidine,and 2,4,6-Triazidopyridine as Precursors of Carbon Nitride Materials

The thermolysis of 2,4,6-triazido-1,3,5-triazine (I), 2,4,6-triazidopyrimidine (II), and 2,4,6-triazidopyridine (III) and its products were studied by DSC, mass spectrometry, IR spectroscopy, and electron microscopy. The thermal transformations of I gave planar nets formed by polyconjugated C–N bonds arranged into bundle aggregates. The thermolysis product of III consists of low-molecular compounds and has globular morphology. The thermolysis of II resulted in a mixture of products of both types, among which the planar nets were dominant. The relationship between the structure of the products of the thermal transformations of I, II, and III and the kinetic characteristics of these processes was discussed.     

Spin-frustrated antiferromagnets based on <Emphasis Type="Italic">BEDT-TTF</Emphasis> and manganese dicyanamide complexes

The magnetic properties of new radical cation salts (BEDT-TTF)₂[CuMn(dca)₄] (I) and (BEDT-TTF)₂[Mn(dca)₃] (II) [where BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene and dca = N(CN₂)] are investigated using superconducting quantum interference device (SQUID) magnetometry and electron paramagnetic resonance (EPR) spectroscopy. It is established that, at temperatures below 25 K, both salts are characterized by antiferromagnetic deviations from the paramagnetic behavior. The Weiss constants for compounds I and II are determined to be ?5 and ?10 K, respectively. The corresponding correlations in the structure of compound I are short-range correlations and do not lead to a change in the effective spin equal to 5/2. It is found that the widths of the EPR lines attributed to the BEDT-TTF conducting sublattice correlate with the widths of the EPR lines associated with the magnetic sublattice of the Mn(dca) ₃ ^? counterion in the structure of salt II. This correlation suggests that the antiferromagnetic ordering in the magnetic sublattice of compound II affects the spin-lattice relaxation in the BEDT-TTF sublattice. The dependence of the magnetic moment on the magnetic field for compound II at a temperature of 2 K is typical of weakly frustrated uniaxial antiferromagnets and exhibits a kink in a magnetic field of 20 kOe, which corresponds to spin-flop transitions.     

Some exact solutions of the local induction equation for the motion of a vortex in a Bose–Einstein condensate with a Gaussian density profile

The dynamics of a vortex filament in a Bose–Einstein condensate whose equilibrium density in the reference frame rotating at the angular velocity Ω is Gaussian with the quadratic form r·D?r has been considered. It has been shown that the equation of motion of the filament in the local-induction approximation permits a class of exact solutions in the form R(β, t) = βM(t) + N(t) of a straight vortex, where β is the longitudinal parameter and is the time. The vortex slips over the surface of an ellipsoid, which follows from the conservation laws N · D?N=C ₁ and M · D?N=C ₀=0. The equation of the evolution of the tangential vector M(t) appears to be closed and has integrals of motion M ·D?M=C ₂ and (|M| ? M· G?Ω) = C, with the matrix G? = 2(I?TrD? ? D?)^?1. Crossing of the respective isosurfaces specifies trajectories in the phase space.     

An efficient and facile synthesis of new tetracyclic fused pyrazolo[4,3-<Emphasis Type="Italic">c</Emphasis>][1,2,4]triazino[4,5-<Emphasis Type="Italic">a</Emphasis>]quinolin-4(5<Emphasis Type="Italic">H</Emphasis>)-ones

Reaction of amidrazones 1a–1i with (1,5-dihydro-3-methyl-5-oxo-1-phenyl-4H-pyrazol-4-ylidene)propanedinitrile (2) in ethyl acetate solution in one-step reaction led to the formation of unprecedented pyrazolo[4,3-c][1,2,4]triazino[4,5-a]quinolin-4(5H)-ones 3a–3g along with pyrazolo[4,3-c][1,2,4]triazino[4,5-a]quinolin-12b-oles 3h–3m in moderate to excellent yields. These novel heterocycles were formed via a Michael addition reaction followed by intramolecular cyclization via a dearomatization process.     

A Highly Selective and Sensitive Fluorescent Chemosensor for Aluminum Ions Based on Schiff Base

An efficient “off–on” type fluorescent chemosensor, (E)-N′-(4-(diethylamino)-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (H ₂ L), based on Schiff base for the determination of Al³⁺ has been designed, synthesized, and evaluated. Upon treated with Al³⁺, the fluorescence of H ₂ L was enhanced 45-fold due to the chelation-enhanced fluorescence (CHEF) effect based on the formation of a 1:1 complex between the chemosensor and Al³⁺. Other metal ions, such as Na⁺, K⁺, Mg²⁺, Ca²⁺, Cu²⁺, Ga³⁺, Zn²⁺, Cr³⁺, Cd²⁺, Ag⁺, Fe³⁺, In³⁺, Mn²⁺, Pb²⁺, Co²⁺, and Ni²⁺ had little effect on the fluorescence. The results demonstrate that the chemosensor H ₂ L has stronger affinity with Al³⁺ than other metal ions. The detection limit of H ₂ L for sensing Al³⁺ is 3.60 × 10^?6 M in EtOH–H₂O (3:7, v/v) solution. And the recognizing behavior has been investigated both experimentally and computationally.     

Pseudogap in the spin-polaron approach for the carrier spectrum of a two-dimensional doped antiferromagnet

In the Kondo model of the two-dimensional lattice with a strong spin-hole antiferromagnetic exchange, the pseudogap behavior of the carrier spectral function A(k, ω) is considered in the optimal and almost dielectric doping limits. A distinctive feature of the analysis is the introduction of the spin polaron even in the mean-field approximation that leads to the formation of two bands (the analogs of the upper and lower Hubbard bands) and makes it possible to immediately take into account the main rearrangement of A(k, ω). The inclusion of the scattering of the mean-field polaron (within the irreducible Green’s functions) describes the further rearrangement of A(k, ω), in particular, the unusual appearance of the pseudogap near the points N = (±π/2, ±π/2).     

A f acile,regioselective synthesis of novel 3-( N-phenylc arbox amide)pyr azolo[1,5- a]pyrimidine an alogs in the presence of KHSO$$_{}$$ in aqueous medi a assisted by ultr asound and their antib acteri al activities

An environmentally benign, simple, efficient, and convenient route is described for the synthesis of novel pyrazolo[1,5-a]pyrimidine derivatives under ultrasound irradiation. Condensation of aminopyrazole 5 with formylated active proton compounds (6, 8, E–G, 12, and 15) furnished pyrazolopyrimidine (7, 9, 10, 13, and 16) in high-to-excellent yields. In comparison with conventional methods, ultrasound irradiation offers several advantages, such as shorter reaction time, higher yields, milder conditions, and environmental friendliness. The reaction is clean with excellent yields and reduces the use of solvents. X-ray crystallographic study of compound 7c confirmed the regioselectivity of the reaction. The antibacterial profile of the newly synthesized compounds was evaluated by cup and saucer method.     

Coumarin Based Fluorescent Probe for Colorimetric Detection of Fe<Superscript>3+</Superscript> and Fluorescence Turn On-Off Response of Zn<Superscript>2+</Superscript> and Cu<Superscript>2+</Superscript>

A new coumarin based Schiff-base chemosensor-(E)-7-(((8-hydroxyquinolin-2-yl)methylene) amino)-4-methyl-2H-chromen-2-one (H ₁₁ L) was synthesized and evaluated as a colorimetric sensor for Fe³⁺ and fluorescence “turn on-off” response of Zn²⁺ and Cu²⁺ using absorption and fluorescence spectroscopy. Upon treatment with Fe³⁺ and Zn²⁺, the absorption intensity as well as the fluorescence emission intensity increases drastically compared to other common alkali, alkaline earth and transition metal ions, with a distinct color change which provide naked eye detection. Formation of 1:1 metal to ligand complex has been evaluated using Benesi-Hildebrand relation, Job’s plot analyses, ¹H NMR titration as well as ESI-Mass spectral analysis. The complex solution of H ₁₁ L with Zn²⁺ ion exhibited reversibility with EDTA and regenerate free ligand for further Zn²⁺ sensing. H ₁₁ L exhibits two INHIBIT logic gates with two different chemical inputs (i) Zn²⁺ (IN1) and Cu²⁺ (IN2) and (ii) Zn²⁺ (IN1) and EDTA (IN2) and the emission as output. Again, an IMPLICATION logic gate is obtained with Cu²⁺ and EDTA as chemical inputs and emission as output mode. Both free ligand as well as metal-complexes was optimized using density functional theory to interpret spectral properties. The corresponding energy difference between HOMO-LUMO energy gap for H ₁₁ L, H₁₁L-Zn²⁺ and H₁₁L-Cu²⁺ are 2.193, 1.834 and 0.172 eV, respectively.     

The dynamic structure of <Emphasis Type="Italic">cis</Emphasis> and <Emphasis Type="Italic">trans</Emphasis> conformers of substituted phosphinous acids

The potential energy surfaces of bis-(trifluoromethyl)-phosphinous (III), diemthylphosphinous (IV), and bis-(pentafluorophenyl)-phosphinous (V) acids, the geometric parameters of the cis and trans conformers of these acids, and their P-O and O-H stretching vibration frequencies were calculated by the density functional theory method (PBE, 4Z). The potential energy surface sections corresponding to internal rotations about the P-O bonds were constructed, and dynamic problems for such a motion of the proton in a cyclic potential were solved by the Ritz method using a basis set of 100 trigonometric functions. According to calculations, the energy differences between the cis and trans conformers of acids III–V were of 4–7 kJ/mol, and the heights of potential barriers separating these conformers were of from 11 to 16 kJ/mol. In acids III and V, the cis, and, in IV, the trans conformer was stabler. At 298 K, only the ground vibrational states were populated for both rotamers of IV and V and the cis conformer of III. The special features of the potential of III were such that, at 298 K, the first excited vibrational level of its trans conformer was also noticeably populated.     

Synthesis,in vitro $$\alpha $$-glucosidase inhibitory activity,and in silico study of ( E)-thiosemicarbazones and ( E)-2-(2-(arylmethylene)hydrazinyl)-4-arylthiazole derivatives

This study is focused on the identification of thiazole-based inhibitors for the \(\alpha \)-glucosidase enzyme. For that purpose, (E)-2-(2-(arylmethylene)hydrazinyl)-4-arylthiazole derivatives were synthesized in two steps and characterized by various spectroscopic techniques. All derivatives and intermediates were evaluated for their in vitro \(\alpha \)-glucosidase inhibitory activity. Thiosemicarbazones 20 and 35, and cyclized thiazole derivatives 2, 5–11, 13, 15, 21–24, 27–31, and 36–37 showed significant inhibitory potential in the range of \(\hbox {IC}_{50}=6.2\pm 0.19\)–\(43.6\pm 0.23~\upmu \hbox {M}\) as compared to standard acarbose (\(\hbox {IC}_{50}=37.7\pm 0.19~\upmu \hbox {M}\)). A molecular modeling study was carried out to understand the binding interactions of compounds with the active site of enzyme.     

Synthesis of new chiral 1,3,4-thiadiazole-based di- and tri-arylsulfonamide residues and evaluation of in vitro anti-HIV activity and cytotoxicity

A series of new chiral 1,3,4-thiadiazole-based bis-sulfonamides 4a–4w and tri-sulfonamide analogue 5 was synthesized and evaluated as anti-HIV agents. The reaction of chiral amino acids 1 with sulfonyl chlorides 2, followed by subsequent reaction of resultant N-protected amino acids 2a–2f with thiosemicarbazide in the presence of excess phosphorous oxychloride afforded N-(1-(5-amino-1,3,4-thiadiazol-2-yl)alkyl)-4-arylsulfonamides 3a–3f. Treatment of 2a–2f with substituted sulfonyl chlorides in portions furnished the target bis-sulfonamide analogues 4a–4w in good yields, together with the unexpected 5. The new compounds were assayed against HIV-1 and HIV-2 in MT-4 cells. Compounds 4s were the most active in inhibiting HIV-1 with IC₅₀?=?9.5 μM (SI?=?6.6), suggesting to be a new lead in the development of an antiviral agent. Interestingly, compound 5 exhibited significant cytotoxicity of >?4.09 μM and could be a promising antiproliferative agent.     

Effect of a Rare-Earth Ion on the Structural Instability in RFe<Subscript>3</Subscript>(BO<Subscript>3</Subscript>)<Subscript>4</Subscript> Crystals

The dynamics of the crystal lattice of RFe₃(BO₃)₄ (R = Pr, Nd, Sm, Gd, Tb, Dy, and Ho) compounds in the high-symmetry R32 phase has been calculated. Significant changes in spectra of compounds with various rare-earth ions have been obtained only near the edge Λ point of the Brillouin zone (qΛ = 1/3(?2b₁ + b₂ + b₃, where b₁, b₂, and b₃ are the reciprocal lattice vectors) for acoustic oscillation branches. A decrease in the frequency of an acoustic mode at the point Λ has been revealed in all studied compounds. This frequency depends on the type of rare-earth ion and decreases from a compound with Pr to a compound with Ho down to imaginary values. Such a behavior of the frequency of the unstable acoustic mode is in good agreement with experimental data on the dependence of the temperature of the R32 → P3₁21 structural phase transition on the type of rare-earth ion in ferroborates.     

Design and one-pot synthesis of 2-thiazolylhydrazone derivatives as influenza neuraminidase inhibitors

Two series of novel 2-thiazolylhydrazone derivatives were designed and synthesized via one-pot reaction of benzaldehyde derivatives, \(\alpha \)-haloketones and thiosemicarbazide. The structures of compounds 1 and 2 were characterized by \(^{1}\hbox {H}\) NMR and \(^{13}\hbox {C}\) NMR, and compound 1g was further confirmed by X-ray crystallography. All of the target compounds were evaluated for their NA inhibitory activity against influenza viral neuraminidase (H1N1) in vitro, and the results showed that many compounds exhibited moderate to strong inhibitory activities against influenza viral neuraminidase (H1N1). Among them, compounds 1p, 1q and 2c showed the most potent inhibitory activities with \(\hbox {IC}_{50}\) values ranging from 10.50 to \(13.75\, \upmu \hbox {g}/\hbox {mL}\). Our structure–activity relationship analysis indicated that 2-thiazolylhydrazone is an effective scaffold for NA inhibitors and that introducing an ethoxycarbonyl group to the 5-position of thiazole ring could enhance inhibitory potency. Molecular docking was performed on the most active compounds 1p and 2c to provide more insight into their mechanism of interaction.     

Preparation of Different Substitued Polypyridine Ligands,Ruthenium(II)-Bridged Complexes and Spectoscopıc Studies

Novel different substitued polypyridine ligands 4-((4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)phenoxy)methyl)benzaldehyde (BA-PPY), (E)-N-(4-((4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)phenoxy)methyl)benzylidene)-pyrene-4-amine (PR-PPY), (E)-N-(4-((4-(1H-imidazo[4,5-f][1,10] phenanthroline-2-yl)phenoxy)methyl)benzylidene)-1,10-phenanthroline-5amine (FN-PPY), 2-(4-(bromomethyl)phenyl)-1H-imidazo[4,5-f][1,10] phenanthroline (BR-PPY), 2-(4-(azidomethyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (N3-PPY) and triazole containing polypyridine ligand 3,4-bis[(4-(metoxy)-1,2,3-triazole)1-methylphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline)] benzaldehyde (BA-DIPPY) and Ruthenium(II) complexes were synthesized and characterized. Their photopysical properties were investigated. The complexes RuP(PR-PPY), RuB(PR-PPY, RuP(FN-PPY) and RuB(FN-PPY) exhibited a broad absorption bands at 485, 475, 476, and 453 nm, respectively, assignable to the spin-allowed MLCT (d_π–π*) transition. The emission maxima of the pyrene-appended polypyridine ligand PR-PPY was observed at λems = 616 nm and the phenanthroline-appended polypyridine ligand FN-PPY was observed at λems = 668 nm. And the emission maxima of the complexes RuP(PR-PPY), RuB(PR-PPY), RuP(FN-PPY) and RuB(FN-PPY) were observed at λems = 646, 646, 685 and 685 nm, respectively. As seen in fluorescence spectra, the fluorescence intensities of the ligands are higher than their metal complexes. This is because of quenching effect of Ruthenium(II) metal on chromophore groups.     

Selective and Sensitive Fluorescent Detection of Picric Acid by New Pyrene and Anthracene Based Copper Complexes

New pyrene and anthracene based copper complexes 4 and 7 respectively were designed, synthesized and characterized. The fluorescence behaviour of both 4 and 7 were evaluated towards nitro aromatics and anions. Both 4 and 7 possess high selectivity for the detection of well-known explosive picric acid (PA) by showing maximum fluorescence affinity. Furthermore, complex 4 showed similar sensing efficiency towards PA at different pH ranges. It was also used for real world applications, as illustrated by the very fast detection of PA from soil samples observed directly by naked eye.     

Comparative study of the structural and spectral properties of tetraaza- and tetraoxaannelated tetracirculenes

The IR spectrum of a recently synthesized tetraaza[8]circulene (4N) molecule has been investigated and completely interpreted based on the calculation of the molecular structure and force field within the density functional theory (DFT) using the B3LYP/6-311G(d,p) method. The calculation has also successfully explained the X-ray diffraction data. The same method has been used to calculate the tetraoxa[8]circulene (4О) molecule and perform a comparative analysis of the IR spectra of both molecules. In contrast to 4О, the 4N molecule exhibits strong fluorescence, which hinders measurement of its Raman spectrum; hence, it is only predicted based on the DFT calculation in this study. A comparison of the IR and Raman spectra of the 4N molecule with the experimental and theoretical analogs for the 4О molecule has made it possible to assign all the observed vibrational transitions and explain the nature of normal vibrations in these complex molecules.