Structural Changes in CuII Complexes of Potential Octadentate Ligands by Coordination with Carboxylate/Carboxylic Acid: DFT, TD-DFT, and Experimental Studies

2010 ◽  
Vol 63 (6) ◽  
pp. 965 ◽  
Author(s):  
Enrique Montiel ◽  
Julian Cruz ◽  
Narayanan Jayanthi ◽  
Sylvain Bernés ◽  
Thangarasu Pandiyan
Keyword(s):  
Carboxylic Acid ◽  
Metal Ion ◽  
Density Functional ◽  
Structural Changes ◽  
Experimental Studies ◽  
Spectroscopic Studies ◽  
Td Dft ◽  
Axial Bond ◽  
Geometrical Change ◽  
Molecular Orbital Analysis

The structural and spectroscopic studies of N,N,N′,N′,N′-pentakis-(benzimidazol-2-yl-methyl)diethylenetriamine (L1) and N,N,N′,N′-tetrakis-(benzimidazol-2-yl-methyl)-N′-(carboxylmethyl)diethylenetriamine (L2H) and [CuL1]2+, [CuL2H]2+, and [CuL2]+ were carried out by density functional theory (DFT) and time-dependant (TD)-DFT techniques. The results show that a geometrical change occurs when carboxylate/carboxylic acid coordinates with the metal ion. For example, the ligand L2H forms an octahedral geometry with CuII and in the structure, four nitrogens (N3, N13, N44, N47) are equatorially coordinated with the metal ion, and atoms O50 (–COOH) and N41, which are weakly bonded at the axial positions, are in competition in the formation of an axial bond with CuII; however, for the ligand L2, only a square pyramidal (SP) geometry results with CuII because of the formation of a strong axial bond by O50 (–COO–) with CuII, which dictates non-bonding at its trans position. Molecular orbital analysis proves that both HOMO and HOMO – 1 are localized over the carboxylate ion that favours a strong axial bond with the metal ion; thus, the SP geometry results in the X-ray structure of [CuL2]ClO4. Furthermore, for the complexes, since the electronic spectroscopic bands were unseparated in the spectra, the TD-DFT was used to identify the bands.

scholarly journals Direct Orange 26 Dye Environmental Degradation: Experimental Studies (UV, Mass and Thermal) in Comparison With Computational Exploration Hydrogen Bonding Analysis of TD-DFT Calculations

2021 ◽  
Author(s):  
Zahraa A. M. Abo-Ayad ◽  
Mohamed A. Zayed ◽  
Mahmoud A Noamaan
Keyword(s):  
Hydrogen Bonding ◽  
Dft Calculations ◽  
Density Functional ◽  
Chemical Reactivity ◽  
Population Analysis ◽  
Experimental Studies ◽  
Calculated Data ◽  
Structure Stability ◽  
Vibrational Properties ◽  
Td Dft

Abstract The importance of this study stems from, it concentrates on new approach applying both practical and theoretical aspects to study structure stability of Direct orange dye 26 (DO26) as an important dye widely used for dyeing of cotton or viscose for red orange direct printing. The stable dyes are so difficult to remove, decolorized and/ or degrade, in pure solution or in wastewater samples, without using powerful removal environmental techniques electrochemical oxidations suggest and efficiently used in our Lab. Therefore, it is very important to compare between practical thermal and mass results as efficient techniques in studying dye stability, in comparison with theoretical results using Gaussian program for structural stability identification of DO26 dye, via careful inspection of various phenomena detected in its two symmetrical arms around urea center. Direct orange dye 26 (DO26) structure has been studied applying both practical spectroscopic and theoretical investigations. DFT-B3LYP/6-311++G(d,p) calculations and the electronic vibrational properties are performed to investigate its structure stability and consequently its degradation and removal from its environmental media. Correlation is found between experimental and calculated data. An intra-molecular hydrogen bonding interaction had been detected and characterized in dye skeleton. The hydrogen bonding present in the dye structure affecting its vibrational properties had been discussed. Natural population analysis like HOMO and LUMO and high quality molecular electrostatic potential plots along with various electronics had been presented at the same level of theory. Chemical reactivity descriptors from conceptual density functional theory point of view, structure activity relationship descriptor were obtained. The experimental UV/Visible, FT-IR, mass and GC-mass spectral data of the dye DO26 (D1) had been presented. These data had been supported by TD-DFT calculations to simulate the experimental spectra with computing the natural transition orbitals (NTO) and the orbital composition. The variation of charge transfer length (Δr) and variation in its dipole moment with respect to ground state (ΔmCT) had been computed in order to study the charge redistribution due to the excitations. Actually there is a problem that, degradation of this dye in wastewater by different techniques leads to various unknown fragments but on using theoretical possibilities it can be expected what happened in practical work.

scholarly journals Spectroscopic studies on lipoprotein structure modification under oxidative stress

2011 ◽  
Vol 26 (3) ◽  
pp. 167-178 ◽  
Author(s):  
Andreia Tache ◽  
Simona-Carmen Litescu ◽  
Gabriel-Lucian Radu
Keyword(s):  
Free Radicals ◽  
Metal Ion ◽  
Structural Changes ◽  
Oxidation Process ◽  
Spectroscopic Studies ◽  
Oxidative Modification ◽  
Hydroxyl Groups ◽  
Oxidative Damages ◽  
Endogenous Antioxidant

Matrix assisted laser desorption–ionization time of flight (MALDI-ToF) and infrared techniques were used to study oxidative modification of low density lipoproteins (LDL), considered to have the key role in biological process that initiates and accelerates the development of cardiovascular disease. The early identification of lipoperoxidation products creates the opportunity of the efficient prevention of eventual oxidative damages. MALDI analysis of LDL subjected toin vitrooxidation process initiated by 2,2-azobis(2-amidinopropane) dihydrochloride revealed that some fragments of lipoprotein changed the molecular weight by 16 and 32 Da due to the oxygen or hydroxyl groups attachment, and peroxide or hydroperoxide formation, while Fourier Transformed Infrared studies proved that lipoprotein changes its protein secondary conformation from predominantlyα-helix in predominantlyβ-turn. The increase in free radicals concentration correlated to structural changes, and the presence of transitional metal ion, copper (II), in the oxidation process lead to an enhancing of the damaging effects of free radicals on lipoprotein substrate. It was shown that the toxic effects of oxidants are delayed by the presence of glutathione (10 mM), an endogenous antioxidant.

Time dependent-density functional theory (TD-DFT) and experimental studies of UV–Visible spectra and cyclic voltammetry for Cu(II) complex with Et2DTC

2018 ◽  
Vol 1157 ◽  
pp. 463-468 ◽  
Author(s):  
Eliana Maira A. Valle ◽  
Vinicius Gonçalves Maltarollo ◽  
Michell O. Almeida ◽  
Kathia Maria Honorio ◽  
Mauro Coelho dos Santos ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Cyclic Voltammetry ◽  
Density Functional ◽  
Experimental Studies ◽  
Time Dependent ◽  
Functional Theory ◽  
Visible Spectra ◽  
Td Dft ◽  
Uv Visible ◽  
Dependent Density

scholarly journals TD-DFT Simulation and Experimental Studies of a Mirrorless Lasing of Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-diphenylene-vinylene-2-methoxy-5-{2-ethylhexyloxy}-benzene)]

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1430
Author(s):  
Mamduh J. Aljaafreh ◽  
Saradh Prasad ◽  
Mohamad S. AlSalhi ◽  
Raya H. Alhandel ◽  
Reem A. Alsaigh
Keyword(s):  
Dft Calculations ◽  
Density Functional ◽  
Experimental Studies ◽  
Optical Gain ◽  
Functional Theory ◽  
Time Resolved ◽  
Dft Simulation ◽  
Td Dft ◽  
Lowest Unoccupied Molecular Orbital ◽  
Benzene Toluene

In this work, we investigate the TD-DFT simulation, optical, and mirrorless laser properties of conjugated polymer (CP) Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-diphenylene-vinylene-2-methoxy-5-{2-ethylhexyloxy}-benzene)], also known as (PFO-co-PPV-MEHB) or ADS125GE. TD-DFT calculations were performed for three monomer units with truncated tails using time-dependent density functional theory (TD-DFT) calculations. The calculations showed a highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) structure and a very high oscillator strength of 6.434 for the singlet-singlet transition at 374.43 nm. Experimentally, the absorption and fluorescence spectra were examined at various concentrations in verity of solvents, such as benzene, toluene, and hexane. The experimental results obtained in hexane were comparable with theoretical UV-VIS spectra calculated under vacuum. Amplified spontaneous emission (ASE) spectra peaked at approximately 509 nm for CO PFO-co-PPV-MEHB in solution and were obtained at suitable concentrations and pump energies. Additionally, the photochemical stability of this CP and coumarin (C510) were compared. Time-resolved spectroscopy (TRS) studies with a sub-nanosecond resolution were performed for the CO under various pump energies. These results showed the excited state dynamics and single-pass optical gain of CO PFO-co-PPV-MEHB.

scholarly journals Synthesis, characterization, DFT, and TD-DFT studies of (E)-5-((4,6-dichloro-1,3,5-triazin-2-yl)amino)-4-hydroxy-3-(phenyldiazenyl)naphthalene-2,7-diylbis(hydrogen sulfite)

2021 ◽  
Vol 3 (7) ◽  
Author(s):  
Hitler Louis ◽  
Obieze C. Enudi ◽  
Joseph O. Odey ◽  
Izubundu B. Onyebuenyi ◽  
Azuaga T. Igbalagh ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Nbo Analysis ◽  
Basis Set ◽  
Orbital Interactions ◽  
B3lyp Method ◽  
Td Dft ◽  
Donor Acceptor ◽  
Molecular Orbital Analysis

AbstractIn this study, (E)-5-((4,6-dichloro-1,3,5-triazin-2-yl)amino)-4-hydroxy-3-(phenyldiazenyl)naphthalene-2,7-diylbis(hydrogen sulfite), a cyanurated H-acid (CHA) azo dye, was synthesized and characterized using FT-IR spectrophotometer and GC-MS spectroscopy. A density functional theory (DFT) based B3LYP and CAM-B3LYP method with 6–311 + G (d,p) basis set analysis was computed for HOMO-LUMO, natural bonding orbitals (NBO), UV-Vis absorptions and excitation interactions, in order to understand its molecular orbital excitation properties. A low Energy gap (Eg) of 2.947 eV was obtained from the molecular orbital analysis, which showed that HOMO to LUMO transition is highly feasible; hence CHA is adequate for diverse electronic and optic applications. Studies of the first five excitations (S0 → S1/S2/S3/S4/S5) of CHA revealed that S0 → S1 and S0 → S3 are π → π* type local excitations distributed around the –N=N– group; S0 → S2, a Rydberg type local excitation; S0 → S4, a highly localized π → π* excitation; while S0 → S5 is an n → π* charge transfer from a benzene ring to –N=N– group. From NBO analysis, we obtained the various donor–acceptor orbital interactions contributing to the stabilization of the studied compound. Most significantly, some strong hyper-conjugations (n → n*) within fragments, and non-bondingand anti-bonding intermolecular (n → n*/π* and π → n*/π*) interactions were observed to contribute appreciable energies. This study is valuable for understanding the molecular properties of the azo dyes compounds and for synthesizing new ones in the future.

Investigation of charge transfer complexes formed between (S, S)-bis-N,N-sulfonyl bis-L-phenylalanine dimethylester donor with tetracyanoethylene and chloranil as π-acceptors: Experimental and DFT studies

2016 ◽  
Vol 15 (01) ◽  
pp. 1650009 ◽  
Author(s):  
Messaouda Mohamdi ◽  
Nadjia Bensouilah ◽  
Mohamed Abdaoui
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Population Analysis ◽  
Electronic Spectroscopy ◽  
Experimental Studies ◽  
Spectrophotometric Titration ◽  
Charge Transfer Complexes ◽  
Geometrical Structures ◽  
Functional Theory ◽  
Td Dft

Two novel charge transfer complexes CTC ([D[Formula: see text]TCNE] and [D[Formula: see text]CHL] : D [Formula: see text] (S, S)-bis-N,N-sulfonyl bis-L-phenylalanine dimethylester; TCNE [Formula: see text] Tetracyanoethylene; CHL [Formula: see text] Chloranil) were synthesized and characterized by elemental analysis: Electronic absorption, spectrophotometric titration, IR. The obtained results indicate the formation of 1:1 for both complexes. The experimental studies were complemented by quantum chemical calculations at DFT/CAM-B3LYP level of theory. Optimized geometrical structures, the electronic spectroscopy, excited-state properties and the descriptions of frontier molecular orbitals were computed and discussed by time-dependent density functional theory (TD-DFT). In addition, vibrational frequency calculations, the natural population analysis (NPA) confirms the presence of intermolecular interactions and natural bonding orbitals (NBO) calculation was carried out in order to elucidate the interactions between TCNE [Formula: see text]-acceptor and donor molecule.

scholarly journals Dinuclear Silver(I) Nitrate Complexes with Bridging Bisphosphinomethanes: Argentophilicity and Luminescence

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 881
Author(s):  
Kristina F. Baranova ◽  
Aleksei A. Titov ◽  
Oleg A. Filippov ◽  
Alexander F. Smol’yakov ◽  
Alexey A. Averin ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Structural Changes ◽  
Functional Theory ◽  
Emission Profile ◽  
Td Dft ◽  
Additional Ligand ◽  
Ligand Coordination ◽  
Nitrate Complexes ◽  
Silver Atoms

Two silver nitrate complexes with bisphosphines were obtained and characterized: [Ag(dcypm)]2(NO3)2 (1; dcypm = bis(dicyclohexylphosphino)methane) and [Ag(dppm)]2(Me2PzH)n(NO3)2 (n = 1, 2a; n = 2, 2b; dppm = bis(diphenylphosphino)methane, Me2PzH = 3,5-dimethylpyrazole). The steric repulsions of bulky cyclohexyl substituents prevent additional ligand coordination to the silver atoms in 1. Compounds obtained feature the bimetallic eight-member cyclic core [AgPCP]2. The intramolecular argenthophilic interaction (d(Ag···Ag) = 2.981 Å) was observed in complex 1. In contrast, the coordination of pyrazole led to the elongation of Ag···Ag distance to 3.218(1) Å in 2a and 3.520 Å in 2b. Complexes 1 and 2a possess phosphorescence both in the solution and solid state. Time-dependent density-functional theory (TD-DFT) calculations demonstrate the origin of their different emission profile. In the case of 1, upon excitation, the electron leaves the Ag–P bonding orbital and locates on the intramolecular Ag···Ag bond (metal-centered character). Complex 2a at room temperature exhibits a phosphorescence originating from the 3(M + LP+N)LPhCT state. At 77 K, the photoluminescence spectrum of complex 2a shows two bands of two different characters: 3(M + LP+N)LPhCT and 3LCPh transitions. The contribution of Ag atoms to the excited state in both complexes 2a and 2b decreased relative to 1 in agreement with the structural changes caused by pyrazole coordination.

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