DFT study of the structure and spectral behavior of new pt(II) complexes with 5‐methyl‐5(4‐pyridyl)hydantoin

Platinum complexes are a great interest of study, because of the antitumor activity and the clinical use of some of them in the recent anticancer chemotherapy. In many cases, computational studies can be very useful for predicting the structure and some physicochemical properties of metal complexes. Theoretical calculations can also be used for the rational design of new complexes with optimal ratio: antitumor activity/toxicity. The geometry of three new Pt(II) complexes with general formula cis‐[PtL₂X₂] (where L is 5‐methyl‐5(4‐pyridyl)hydantoin and X = Cl^?, Br^?, I^?) and of the free organic ligand were optimized using the hybrid DFT method B3LYP with LAN2DZ basis sets. The results were in very good correlation with the data of similar compounds from the literature. The same DFT method was used for the study of their spectral behavior, by reproducing their IR and Raman spectra and comparing them with experimental data. In addition, the distribution of charges by ESP analysis was calculated. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

A New 3D Manganese(II) Coordination Polymer with 4,4‐Dicarboxy‐2,2′‐bipyridine and 1,10‐Phenanthroline: Synthesis,Structural, and Magnetic Properties

A new 3D Mn^II metal‐organic framework compound {Mn(phen)(dcbp)}_n (H₂dcbp = 4,4‐dicarboxy‐2,2′‐bipyridine, phen = 1,10‐phenanthroline) was isolated under hydrothermal conditions and structurally characterized. In the compound, the dcbp ligand is deprotonated to give a neutral species (metal:ligand with 1:1 stoichiometry). Along the c axis, the neighboring Mn^II ions are linked by two carboxylate bridges in µ₂‐coordinating mode to generate a 1D zigzag chain, and these chains are interlinked by dicarboxylate groups of long dcbp ligands to generate a 3D (4,4)‐connected structure with the (4².8⁴) net topology. IR and UV/Vis spectroscopy and variable temperature magnetic susceptibility measurements were made, which indicated weak antiferromagnetic interactions between the Mn^II ions of the compound.     

Synthesis,Crystal Structure and Spectroscopic Properties of [2,13‐Bis(1‐naphthalenylmethyl)‐5,16‐dimethyl‐2,6,13,17‐tetraazatricyclo(14,4,01.18,07.12)docosane]copper(II) Diperchlorate Acetonitrile Disolvate

The N‐functionalized macrocyclic ligand 2,13‐bis(1‐naphthalenylmethyl)‐5,16‐dimethyl‐2,6,13,17‐tetraazatricyclo(14,4,0^1.18,0^7.12)docosane (L³) and its copper(II) complex were prepared. The crystal structure of [Cu(L³)](ClO₄)₂·2CH₃CN was determined by single‐crystal X‐ray diffraction at 150 K. The copper atom, which lies on an inversion centre, has a square planar arrangement and the complex adopts a stable trans‐III configuration. The longer distance [2.081(2) Å] for Cu–N(tertiary) compared to 2.030(3) Å for Cu–N(secondary) may be due to the steric effect of the attached naphthalenylmethyl group on the tertiary nitrogen atom. Two perchlorate ions are weakly attached to copper in axial sites and are further connected to the ligand of the cation through NH ··· O hydrogen bonds [N ··· O 3.098 Å]. IR and UV/Vis spectroscopic properties are also described.     

Intrakonfigurations‐, Trip‐Multiplett‐ sowie anomal polarisierte A1gund A2g‐Übergänge in elektronischen und vibratorischen Resonanz‐Raman‐Spektren von (spinentarteten) trans‐Di(cyano)phthalocyaninatorhenaten

Intraconfigurational, Trip‐Multiplet, and Anomalously Polarised A_1g and A_2g Transitions in Electronic and Vibrational Resonance Raman Spectra of (Spin‐Degenerate) trans ‐Di(cyano)phthalocyaninatorhenates Brown bis(tetra(n‐butyl)ammonium) trans‐di(cyano)phthalocyaninato(2‐)rhenate(II) ( 1 ) is prepared by melting bis(phthalocyaninato(2‐)rhenium(II)) with tetra(n‐butyl)ammonium cyanide. According to electrochemical data, 1 is oxidised by iodine to yield blue tetra(n‐butyl)ammonium trans‐di(cyano)phthalocyaninato(2‐)rhenate(III) ( 2 ), whose cation exchange in the presence of bis(triphenylphosphine)iminium salts has been confirmed by x‐ray structure determination. 1 and 2 dissolve without dissociation of the cyano ligands in conc. sulfuric acid. Dilution with cold water precipitates blue trans‐di(cyano)phthalocyaninato(2‐)rhenium(III) acid. 1 and 2 are oxidised by bromine yielding violet trans‐di(cyano)phthalocyaninato(1‐)rhenium(III). Oxidation of 2 with dibenzoylperoxide and N‐chlorsuccinimide is described. 1 and 2 are characterised by polarised resonance Raman(RR) spectra, FIR/MIR spectra, and UV‐Vis‐NIR spectra. Due to a Kramers degenerate ground electronic state of low‐spin Re^II, a polarisation anomaly of the totally symmetric vibrations a_1g at 598 and 672 cm^–1 with depolarisation ratios ρ_l > 3 is observed in the RR spectra of 1 . Weak bands in the unusual UV‐Vis‐NIR spectrum of 1 , starting at 10200 cm^–1, are attributed to trip‐multiplet (TM) transitions. An electronic RR effect is detected for 2 . The selectively enhanced anomalously polarised line at 1009 cm^–1 with ρ_l ≈ 15 and the (de)polarised lines between 1688 and 2229 cm^–1 are attributed to intraconfigurational transitions A_1g → A_2g > A_1g, B_1g, B_2g, E_g arising from the ³T_1g ground electronic state of low‐spin Re^III split by spin‐orbit coupling and low symmetry (D ). Some of their vibronic bands are detected in the IR spectrum between 1900 and 4000 cm^–1. B and Q transitions of 2 at 16700 and 31900 cm^–1, respectively, as well as eight weak TM transitions are observed between 5050 and 26100 cm^–1.     

Crystal Structure and Spectroscopic Properties of trans‐Dibromidobis(propane‐1, 3‐diamine)chromium(III) Perchlorate

The structure of trans‐[Cr(tn)₂Br₂]ClO₄ (tn = propane‐1, 3‐diamine) has been determined by a single‐crystal X‐ray diffraction study at 100 K. The complex crystallizes in the space group P$\bar{1}$ of the triclinic system with two mononuclear formula units in a cell of dimensions a = 6.8220(4), b = 8.86199(9), c = 12.6644(8) Å and α = 77.859(7)°, β = 81.765(6)°, and γ = 77.764(7)°. The chromium atom is in a slightly distorted octahedral environment coordinated by four nitrogen atoms of two tn ligands and two bromine atoms in trans positions. The two six‐membered chelate rings in the complex cations are oriented in an anti chair‐chair conformation with respect to each other. The mean Cr–N(tn) and Cr–Br bonds are 2.093(3) and 2.4681(4) Å, respectively. The crystal packing is stabilized by hydrogen bonds. The infrared and electronic absorption spectral properties are consistent with the result of X‐ray crystallography. It is confirmed that the nitrogen atoms of the tn ligand are strong σ‐donors, but the bromido ligands have weak σ‐ and π‐donor properties toward the chromium(III) ion.     

Synthesis,Structure, and Electronic Properties of Extended π‐Conjugated Group 6 Fischer Alkoxy–Bis(carbene) Complexes

The synthesis, structure and electronic properties of novel Group 6 Fischer alkoxy–bis(carbene) complexes are reported. The UV/Vis spectra of these species display two main absorptions at approximately 350 and 550 nm attributable to a ligand‐field (LF) and metal‐to‐ligand charge‐transfer (MLCT) transitions, respectively. The planarity of the system and the cooperative effect of both pentacarbonyl metal moieties greatly enhance the conjugation between the group at the end of the spacer and the metal carbene fragment provoking dramatic changes in the LF and MLCT absorptions. This is in contrast to related push–pull Fischer monocarbenes, where the position of the MLCT band remains mostly unaltered regardless the substituent attached to the donor fragment. In addition, the MLCT maxima can be tuned with subtle modifications of the electronic nature of the central aryl fragment in the novel A–π‐D–π‐A (A=acceptor, D=donor) systems. DFT and time‐dependent (TD) DFT quantum chemical calculations at the B3LYP/def2‐SVP level have also been performed to determine the minimum‐energy molecular structure of this family of compounds and to analyse the nature of the vertical one‐electron excitations associated to the observed UV/Vis absorptions as well as to rationalise their electrochemical behaviour. The ability of tuning up the electronic properties of the compounds studied herein may be of future use in material chemistry.     

Experimental and quantum chemical calculational studies on N‐[4‐(3‐Methyl‐3‐phenyl‐cyclobutyl)‐thiazol‐2‐yl]‐N′‐pyridin‐3ylmethylene‐hydrazine

The title molecule, N‐[4‐(3‐Methyl‐3‐phenyl‐cyclobutyl)‐thiazol‐2‐yl]‐N′‐pyridin‐3ylmethylene‐ hydrazine (C₂₀ H₂₀ N₄ S₁), was characterized by ¹H‐NMR, ¹³C‐NMR, IR, UV‐visible, and X‐ray determination. In addition to the molecular geometry from X‐ray experiment, the molecular geometry, vibrational frequencies and gauge including atomic orbital ¹H‐ and ¹³C‐NMR chemical shift values of the title compound in the ground state have been calculated using the Hartree‐Fock and density functional method (B3LYP) with 6‐31G(d, p) basis set. The calculated results show that optimized geometries can well reproduce the crystal structural parameters. By using time‐dependent density functional theory method, electronic absorption spectrum of the title compound has been predicted. © 2011 Wiley Periodicals, Inc.     

Charge transfer interactions in polyesters with a donor‐(σ‐bridge)‐acceptor moiety in the repeating unit

Two high molecular weight linear polyesters were investigated to gain insight in how the photophysics of electron donor‐(σ‐spacer)‐electron acceptor (DσA) compounds are affected by incorporation into a polymer. They were prepared by condensation of either adipoyl or sebacoyl chloride with a diol that was functionalized with an N,N‐dialkylaniline donor, a cyclohexyl type σ‐spacer, and a 1,1‐dicyanovinyl acceptor. The solubility, which is very low, and the thermal properties of the polyesters are dictated by physical crosslinking as a consequence of interchain donor‐acceptor interactions. Charge transfer (CT) absorption and emission are observed, which involve CT between DσA moieties of different chains rather than CT processes within a single DσA unit. As a result, the photophysics of the DσA units in the polyesters differs strongly from that of similar DσA compounds in solution. Upon swelling the polymers with THF, the CT fluorescence disappears partly. Analogous polymers containing only an N,N‐dialkylaniline donor display dual fluorescence; one band reflects local emission, while the other is attributed to excimer emission. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4775–4784, 2004     

Plane‐wave density functional theory investigation of adsorption of 2,4,6‐trinitrotoluene on al‐hydroxylated (0001) surface of (4 × 4) α‐alumina

This article reports the results of the theoretical investigation of adsorption of 2,4,6‐trinitrotoluene (TNT) on Al‐hydroxylated (0001) surface of (4 × 4) α‐alumina (α‐Al₂O₃) using plane‐wave Density Functional Theory. Sixteen water molecules were used to hydroxylate the alumina surface. The Perdew–Burke–Ernzerhof functional and the recently developed van der Waals functional (vdW‐DF2) were used. The interaction of electron with core was accounted using the Vanderbilt ultrasoft pseudopotentials. It was found that hydroxylation has significant influence on the geometry of alumina and such changes are prominent up to few layers from the surface. Particularly, due to the Al‐hydroxylation the oxygen layers are decomposed into sublayers and such partitioning becomes progressively weaker for interior layers. Moreover, the nature of TNT adsorption interaction is changed from covalent type on the pristine alumina surface to hydrogen‐bonding interaction on the Al‐hydroxylated alumina surface. TNT in parallel orientation forms several hydrogen bonds compared to that in the perpendicular orientation with hydroxyl groups of the Al‐hydroxylated alumina surface. Therefore, the parallel orientation will be present in the adsorption of TNT on Al‐hydroxylated (0001) surface of α‐alumina. Further, the vdW‐DF2 van der Waals functional was found to be most suitable and should be used for such surface adsorption investigation. © 2014 Wiley Periodicals, Inc.     

Die konjugative Verbrückung metallorganischer Reaktionszentren in Heterozweikernkomplexen [(OC)3ClRe(μ‐L)MCl(C5Me5)]+, M = Rh oder Ir ‐ Spektroskopische Konsequenzen reduktiver Aktivierung

The Conjugative Bridging of Organometallic Reaction Centers in Heterodinuclear Complexes [(OC)₃ClRe(μ‐L)MCl(C₅Me₅)]⁺, M = Rh or Ir ‐ Spectroscopic Consequences of Reductive Activation Heterodinuclear complexes [(OC)₃ClRe(μ‐L)MCl(C₅Me₅)](PF₆), M = Rh or Ir and L = 2, 5‐bis(1‐phenyliminoethyl)pyrazine (bpip), 3, 6‐bis(2‐pyridyl)‐1, 2, 4, 5‐tetrazine (bptz) or 2, 2′‐bipyrimidine (bpym), were synthesized via mononuclear rhenium compounds (L)Re(CO)₃Cl. The stepwise reductive activation under chloride dissociation was studied through cyclic voltammetry and spectroelectrochemistry in the range of CO stretching vibrations (IR), charge transfer absorptions (UV/Vis) and electron spin resonance (ESR) for paramagnetic intermediates of the mono‐ and heterodinuclear compounds. While complexes of bpip and bptz form one‐electron reduced radical intermediates [(OC)₃ClRe(μ‐L)MCl(C₅Me₅)] ^˙ , the compounds with bpym react under MCl‐dissociative two‐electron reduction directly to [(OC)₃ClRe(μ‐L)M(C₅Me₅)].     

A novel series of M(II) complexes of 6‐methylpyridine‐2‐carboxylic acid with 4(5)methylimidazole: Synthesis,crystal structures, α‐glucosidase activity,density functional theory calculations and molecular docking

Novel complexes of 6‐methylpyridine‐2‐carboxylic acid and 4(5)methylimidazole, namely [Mn(6‐mpa)₂(4(5)MeI)₂] ( 1 ), [Zn(6‐mpa)₂(4(5)MeI)₂] ( 2 ), [Cd(6‐mpa)₂(4(5)MeI)₂] ( 3 ), [Co(6‐mpa)₂(4(5)MeI)₂] ( 4 ), [Ni(6‐mpa)₂(4(5)MeI)(OAc)] ( 5 ) and [Cu(6‐mpa)₂(4(5)MeI)] ( 6 ), were synthesized for the first time. The structures of complexes 1 – 4 and complexes 5 and 6 were determined using X‐ray diffraction and mass spectrometric techniques, respectively. The experimental spectral analyses for these complexes were performed using Fourier transform infrared and UV–visible techniques. The α‐glucosidase inhibition activity values (IC₅₀) of complexes 1 – 6 were identified in view of genistein reference compound. Moreover, the DFT/HSEh1PBE/6‐311G(d,p)/LanL2DZ level was used to obtain optimal molecular geometry and vibrational wavenumbers for complexes 1 – 6 . Electronic spectral behaviours and major contributions to the electronic transitions were investigated using TD‐DFT/HSEh1PBE/6‐311G(d,p)/LanL2DZ level with conductor‐like polarizable continuum model and SWizard program. Finally, in order to investigate interactions between the synthesized complexes ( 1 – 6 ) and target protein (template structure S. cerevisiae isomaltase), a molecular docking study was carried out.     

An experimental and theoretical approach to the molecular structure of 3‐{[4‐(3‐Methyl‐3‐phenyl‐cyclobutyl)‐thiazol‐2‐yl]‐hydrazono}‐1,3‐dihydro‐ indol‐2‐one

The title molecule, 3‐{[4‐(3‐methyl‐3‐phenyl‐cyclobutyl)‐thiazol‐2‐yl]‐hydrazono}‐1,3‐dihydro‐indol‐2‐one (C₂₂H₂₀N₄O₁S₁), was prepared and characterized by ¹H NMR, ¹³C NMR, IR, UV–visible, and single‐crystal X‐ray diffraction. The compound crystallizes in the monoclinic space group P21 with a = 8.3401(5), b = 5.6976(3), c = 20.8155(14) Å, and β = 95.144(5)°. Molecular geometry from X‐ray experiment and vibrational frequencies of the title compound in the ground state has been calculated using the Hartree–Fock with 6‐31G(d, p) and density functional method (B3LYP) with 6‐31G(d, p) and 6‐311G(d, p) basis sets, and compared with the experimental data. The calculated results show that optimized geometries can well reproduce the crystal structural parameters, and the theoretical vibrational frequencies values show good agreement with experimental data. Density functional theory calculations of the title compound and thermodynamic properties were performed at B3LYP/6‐31G(d, p) level of theory. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Electronic Excitation of [(μ4‐η2‐alkyne)Rh4(CO)8(μ‐CO)2]: An In Situ UV/Vis Spectroscopy,Spectral Reconstruction and DFT Study

Reactions of three alkynes, namely, 1‐heptyne, 3‐hexyne and 1‐phenyl‐1‐butyne, with [Rh₄(CO)₉(μ‐CO)₃] are performed in anhydrous hexane under argon atmosphere with multiple perturbations of alkynes and [Rh₄(CO)₉(μ‐CO)₃]. The reactions are monitored by in situ UV/Vis spectroscopy, and the collected electronic spectra are further analyzed with the band‐target entropy minimization (BTEM) family of algorithms to reconstruct the pure component spectra. Three BTEM estimates of [(μ₄‐η²‐alkyne)Rh₄(CO)₈(μ‐CO)₂], in addition to that of [Rh₄(CO)₉(μ‐CO)₃], are successfully reconstructed from the experimental spectra. Time‐dependent density functional theory (TD‐DFT) predicted spectra at the PBE0/DGDZVP level are consistent with the corresponding BTEM estimates. The present study demonstrates that: 1) the BTEM family of algorithms is successful in analyzing multi‐component UV/Vis spectra and results in good spectral estimates of the trace organometallics present; and 2) the subsequent DFT/TD‐DFT methods provide an interpretation of the nature of the electronic excitation and can be used to predict the electronic spectra of similar transition organometallic complexes.     

Crystal Structure and Characterization of Two Layered Copper(II) Coordination Polymers with Anions of 3‐Phosphonopropionic Acid and (RS)‐2‐Phosphonobutyric Acid

Blue single crystals of Cu[μ₃‐O₃P(CH₂)₂COOH] · 2H₂O ( 1 ) and Cu[(RS)‐μ₃‐O₃PCH(C₂H₅)COOH] · 3H₂O ( 2 ) were prepared in aqueous solutions (pH = 2.5–3.5). 1 crystallizes in space group Pbca (no. 61) with a = 812.5(2), b = 919.00(9), and c = 2102.3(2) pm. Cu²⁺ is fivefold coordinated by three oxygen atoms stemming from [O₃P(CH₂)₂COOH]^2– anions and two water molecules. The Cu–O bond lengths range from 194.0(3) to 231.8(4) pm. The connection between the [O₃P(CH₂)₂COOH]^2– anions and the Cu²⁺ cations yields a polymeric structure with layers parallel to (001). The layers are linked by hydrogen bonds. 2 crystallizes in space group Pbca (no. 61) with a = 1007.17(14), b = 961.2(3), c = 2180.9(4) pm. The copper cations are surrounded by five oxygen atoms in a square pyramidal fashion with Cu–O bonds between 193.6(4) and 236.9(4) pm. The coordination between [O₃PCH(C₂H₅)COOH]^2– and Cu²⁺ results in infinite puckered layers parallel to (001). The layers are not connected by any hydrogen bonds. Each layer contains both R and S isomers of the [O₃PCH(C₂H₅)COOH]^2– dianion. Water molecules not bound to Cu²⁺ are intercalated between the layers. UV/Vis spectra suggest three d–d transition bands at 743, 892, 1016 nm for 1 and four bands at 741, 838, 957, and 1151 nm for 2 , respectively. Magnetic measurements suggest a weak antiferromagnetic coupling between Cu²⁺ due to a super‐superexchange interaction. Thermoanalytical investigations in air show that the compounds are stable up to 95 °C ( 1 ) and 65 °C ( 2 ), respectively.     

Spectroscopic,DFT and antimicrobial activity of Zn(II), Zr(IV), Ce(IV) and U(VI) complexes of N,N‐ chelated 4,6‐bis (4‐chlorophenyl)‐2‐amino‐1,2‐dihydropyridine‐3‐carbinitrile

Four novel metal complexes of 4,6‐bis (4‐chlorophenyl)‐2‐amino‐1,2‐dihydropyridine‐3‐carbinitrile (H₂L) with Zn(II), Zr(IV), Ce(IV) and U(VI) were synthesized. The structure was elucidated using elemental analysis, melting point, molar conductivity; spectroscopic techniques (IR, ¹H NMR, UV–Vis., mass spectra) as well as thermo gravimetric analysis. The spectroscopic data proved that H₂L chelated with the metal ions as a bidentate ligand through N_amino and N_carbinitrile atoms. The molecular structure of the complexes was determined using density functional theory (DFT). The central metal ion in each complex is six‐coordinate and the angles around it vary from 62.74° to 166.46°; these values agree with distorted octahedral geometry. The calculated total energy of the complexes found in the region – 406.342 to ?459.717 au and the dipole moment change from 4.675 to 13.171D. The antibacterial and antifungal activities of the ligand, metal salts and complexes were estimated on some microorganisms. The complexes showed significant antibacterial profile in comparison to the free ligand.