TD-DFT Calculations Research Articles

Synthesis and Photophysical Properties of 4'-5' Disubstituted CinNapht Dyes Accessible through Double SNAr Late-Stage Functionalization.

This article describes the synthesis of a difluorinated CinNapht derivative in the 4' and 5' positions allowing the easy access to two new families of fluorophores by late-stage functionalization using SNAr. The first one comprises derivatives incorporating hindered aromatic amines in the 4' and 5' positions, which show redemission in apolar solvents. The second one is obtained through the use of dinucleophiles. Among them, Tetrahydroquinoxaline (THQ) and tetrahydrobenzodiazepine (THB) compounds show strongly redshifted emission. The photophysical properties of all the fluorophores in these two families are studied and rationalized by DFT and TDDFT calculations. The most promising compounds have been used to image living cells by confocal microscopy.

Germylene Mediated Reductive C-C and C-N Coupling of an Isocyanide and its Device Application.

We have demonstrated a unique reductive coupling of 4-iodophenyl isocyanide, facilitated by a perimidine-based N-heterocyclic germylene (NHGe), which yields a bis-spirogerma compound featuring simultaneous C-C and C-N bond formation. This reaction, which leads to the oxidation of germanium from +2 to +4, represents a significant departure from previously documented isocyanide-germylene interactions. The product exhibits extensive conjugation across its bicyclic C4Ge2N2 framework, conferring distinct photophysical properties, including prominent orange luminescence in both solution and solid states. The photophysical properties are supported by the TD-DFT calculations confirming an n→π* transition. The potential application of this compound in optoelectronic devices, particularly as a hole transport layer in PbS quantum dot solar cells, is also explored, with promising preliminary results.

Structural and Photophysical Differences in Crystalline Trigonal Planar Copper Iodide Complexes with 1,2-Bis(methylpyridin-2-yl)disilane Ligands.

We synthesized trigonal planar Cu(I) iodide complexes with 1,2-bis(methylpyridin-2-yl)disilane ligands L1-L4 and investigated how the substitution position of the methyl group on the pyridine ring in σ-π conjugation affects their structure and physical properties. The structures were characterized by NMR, elemental analysis, and single-crystal X-ray diffraction. In the crystalline state, the methylpyridyl groups of CuIL1-CuIL3 were coordinated with Cu(I) in an anticlinal conformation relative to the Si-Si σ bond, whereas those of CuIL4 were coordinated with Cu(I) in a synperiplanar conformation relative to the Si-Si σ bond. The conformational difference in the crystalline state was influenced by the N-Cu-N bite angle and the emission wavelength. CuIL1-CuIL3 exhibited blue-green emission (λem: 476-494 nm), and CuIL4 exhibited green-yellow emission (λem: 512 nm) with high emission quantum yields (Φ: 0.59-0.86) in the crystalline state at 293 K. These Cu(I) complexes exhibited thermally activated delayed fluorescence from the S1 state at 293 K and phosphorescence from the T1 state at 77 K in the crystalline state. The optical properties in the crystalline state were discussed by DFT and TD-DFT calculations. These complexes also displayed aggregation-induced emission in THF-water solution (fw > 80%), although they did not show emission in dehydrated THF.

Triphenylamine-based D-A-π-A dyes for DSSC applications: Theoretical study on the impact of auxiliary acceptor groups and π-bridges on photovoltaic performance using DFT and TD-DFT calculations

Triphenylamine-based D-A-π-A dyes for DSSC applications: Theoretical study on the impact of auxiliary acceptor groups and π-bridges on photovoltaic performance using DFT and TD-DFT calculations

A New Proton Transfer Complex Between 3,4-Diaminopyridine Drug and 2,6-Dichloro-4-nitrophenol: Synthesis, Spectroscopic Characterization, DFT Studies, DNA Binding Analysis, and Antitumor Activity.

The proton transfer (PT) complexation reaction between 3,4-diaminopyridine (3,4-DAP), an important drug, and 2,6-dichloro-4-nitrphenole (DCNP) was investigated experimentally and theoretically. The experimental results indicated a chemical reaction occurred because of a hydrogen bonding, followed by proton transfer from the DCNP to the 3,4-DAP in different polar media. The Benesi-Hildebrand equation was used to estimate the formation constant (Kf), molar absorptivity (εPT), and other physical parameters. The formed PT complex was characterized using FTIR, 1H, and 13C NMR spectra. In addition, the nanocrystalline structure, particle sizes, and surface morphology of the complex were investigated by XRD and SEM-EDX. The structure of the 1:1 PT complex was calculated theoretically in the gas phase and the presence of solvent effects. Using TD-DFT calculations, the band observed at 406 nm (Calc. 379.5 nm) and 275 nm (Calc. 272.3 nm) could be assigned to the HOMO→LUMO transition (99%), and HOMO→L+3 transition (87%), respectively. The DNA binding ability of the PT complex was investigated, revealing an intercalative binding mechanism with a binding constant Kb of 4.6 × 104 M-1. Based on the results of the Ct-DNA binding study, the binding free energy of the PT complex with the receptor of human DNA (PDB ID:1BNA) is found to be -7.2 kcal/mol. The cytotoxic effects of the PT complex were evaluated on selected cancer cell lines, demonstrating significant antitumor activity against A-549 and MCF-7 cancer cell lines.

Face-to-Face Gold Porphyrins.

The interaction of square-planar metal complexes through space is of fundamental interest and relevant for the potential cooperative catalysis of two metal complex sites. In order to elucidate gold/gold, gold/porphyrin, and porphyrin/porphyrin interactions in the formal oxidation states +III and +II (after reduction) and in the excited triplet state after light excitation, a Pacman bis(gold(III)) complex [Au2(DPD)][PF6]2 with square-planar face-to-face gold(porphyrin) moieties has been prepared and characterized. Absorption and luminescence spectroscopy, cyclic voltammetry, and EPR spectroscopy on [Au2(DPD)]n+ and a mononuclear reference are complemented by DFT and TDDFT calculations.

Benzo[1,2-b:4,5-b’]dithiophene diethynyl bridged bimetallic ruthenium complexes: syntheses and characterization, (spectro)electrochemistry combined with theoretical calculations

We have constructed isomeric triruthenium ethynyl complexes 1 and 2 linked by benzo[1,2-b:4,5-b’]dithiophene. The electronic properties of 1 and 2 were compared by (spectro)electrochemical and theoretical calculations. DFT (density functional theory) fully-optimized structures 1 and 2 showed that the ruthenium terminal groups both exhibit a similar pseudo-octahedral configuration as reported for the crystal structure of 1. With step-by-step oxidation, the bond length of Ru-C decreases and the bond length of C≡C increases, which indicated that the complexes undergo a transition from Ru-C≡C to Ru = C = C. The electrochemical results of 1 and 2 featured two consecutive single-electron redox processes, and the ΔE value of 2 (329 mV) was significantly higher than that of 1 (140 mV). The near-IR broad absorptions of 2 + from UV-Vis-NIR spectroelectrochemistry exhibited a blue shift relative to that of 1 +, which could be attributed to MLCT (metal to ligand charge transfer) absorptions and confirmed by TDDFT (time dependent) calculations. The results suggested that the bridge ligands are involved in the redox process. The ν(C≡C) stretch of 2 + from IR spectroelectrochemistry exhibited a strong single peak at 1969 cm-1, while the isomer 1 + showed three asymmetric peaks. These results showed excellent charge delocalization ability of 2.

Intrinsic Narrowband Blue Phosphorescent Materials and Their Applications in 3D Printed Self-monitoring Microfluidic Chips.

Organic room-temperature phosphorescent (RTP) materials, especially with narrowband emission properties, exhibit great potential for applications in display and sensing, but have been seldom reported. Herein, a rare example of the intrinsic narrowband blue RTP material is fabricated and reported. A series of indolo[3,2,1-kl]phenothiazine derivatives, named Cphpz, 1O-Cphpz, and 2O-Cphpz, are designed and synthesized. Due to their relatively rigid structures, these three compounds showed deep blue narrowband emissions ranging from 396 to 434nm with the full width at half maximum (FWHM) of 31, 26, and 31nm, respectively. To the delight, compound 2O-Cphpz displayed intrinsic narrowband blue RTP at 448 nm with FWHM of 36 nm and a long-lived lifetime of 1.08 s in hydroxyethyl acrylate and acrylic acid matrix. Photophysical studies, single crystal analyses, and TD-DFT calculations are performed to elucidate further the relationships between molecular structures and the narrowband blue RTP properties. Meanwhile, because the narrowband blue RTP is highly sensitive to humidity, a visualizing droplet path optical microfluidic chip is efficiently fabricated through the digital light processing 3D printing.This work provides a rare example and a reliable strategy to realize narrowband blue RTP and further expand their applications in self-monitoring 3D printed structures.

Synthesis of BODIPY-pyrrolo[3,4-b]pyridin-5-ones via Ugi-Zhu/cascade reactions and studies of fluorescence response toward viscosity.

A series of seven new meso-phenyl BODIPY-pyrrolo[3,4-b]pyridin-5-one conjugates were synthesized in one experimental step by using a Sc(III)-catalyzed Ugi-Zhu three-component reaction coupled to a cascade sequence (aza Diels-Alder/N-acylation/aromatization) as post-MCR functionalization process. Further experimental studies were performed behind understanding the fluorescence response toward viscosity. All compounds exhibited a linear response between increasing viscosity (DMSO and glycerol mixtures) and fluorescence intensity. The different substituents also influenced the photophysical properties. Furthermore, in DMSO all compounds exhibited dual emission. Each band is attributed to the pyrrolo[3,4-b]pyridin-5-one and BODIPY moieties, respectively. The electronic structure of all compounds was computed by DFT and TD-DFT calculations, allowing to determine the molecular orbitals involved in the electronic transitions.

Synthesis of a Multi-Stimulus Responsive RGB Fluorescent Organic Molecule Based on Dark Through-Bond Energy Transfer Mechanism.

In this study, a novel multi-stimulus responsive RGB fluorescent organic molecule, RTPE-NH2, was designed and synthesized based on the combination of aggregation-induced emission tetraphenylethylene (TPE) luminophore and acid-responsive fluorescent molecular switch Rhodamine B. RTPE-NH2 exhibits aggregation-induced emission behavior, as well as UV irradiation-stimulus and acid-stimulus responsive fluorescence properties. It could emit orange-red (R), green(G), and blue(B) light in both solution and PMMA film under 365 nm excitation. The dark through-bond energy transfer (DTBET) mechanism was proposed and supported by control experiments and TD-DFT calculations. The synthesis and application of RTPE-NH2 could accelerate the development of organic smart materials with high sensitivity and excellent optical properties.

First TPymT-Ln complexes (TPymT = 2,4,6-Tris(2-pyrimidyl)-1,3,5-triazine; Ln = Eu, Gd, Tb, Dy): Solvothermal synthesis, structure, magnetic and photoluminescent properties

Four novel mononuclear lanthanide complexes, [Ln(TPymT)(NO3)3(H2O)2] (Ln: Eu3+ (1), Gd3+ (2), Tb3+ (3) and Dy3+ (4)), have been solvothermally synthesized using multidentate 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (TPymT). Compounds 1–3 have been characterized by means of elemental analysis, FT-IR, and single-crystal/powder X-ray diffraction analysis. Compound 4 was structurally characterized. The Ln3+ ion in 1–4 is ten-coordinated, where TPymT serves as an N3 donor in an isostructural series. The alternating-current magnetic studies showed frequency dependence below ca. 10 K for 3, as an indication of a single-ion magnet. The activation energy for the magnetization reorientation was estimated as Ueff/kB = 95(9) K after applying a dc bias field 2000 Oe for 3. The photoluminescent studies clarified that 1 and 3 behaved as red and green light emitters with quantum yields as high as 17 and 39 %, respectively. The TD-DFT calculation supports the energy level scheme of ground and excited states of TPymT together with the reference compound 4′-phenyl-2,2’:6′,2″-terpyridine. The present work suggests a broad chance and motivation to apply TPymT to the field of 4f coordination chemistry.

Non-linear optical properties of hybrid materials of (OLi3) superalkali doped perylene diimide (PDI) derivative: comprehensively study via silico-technique

PDI-Imidazole and PDI-Imidazole combined with OLi3 (OLi3@PDI-Imidazole) were the two types of materials that we examined in this study to see how light behaved in each of the complex. To explore this, we employed the three different method such as rB3LYP/6–31G(d, p) DFT, CAM-B3LYP and WB97XD. The impact of PDI-Imidazole and OLi3@PDI-Imidazole geometries, maximum absorption ( λmax ), FMO, vertical ionization energies ( EVI ), Binding Energies ( Eb ), Hyperpolarizabilities, DOS, Dipole Moments (μ), ESP, EDDM, and Global Reactivity parameters have been examined. The type of contacts as well as the vibrational frequencies of PDI-Imidazole and OLi3@PDI-Imidazole were investigated using NCl, iso-surface, Raman spectroscopy, and IR research. The electron transport characteristics of the OLi3@PDI-Imidazole surface was significantly enhanced in comparison to the PDI-Imidazole surface by lowering the bandgap energies from 1.27 eV to 1.03 eV. In contrast to the pure PDI-Imidazole surface, which had lower values for linear polarizability ( α0 ) (547.08 au) and first hyperpolarizability ( β0 )(201.133au), OLi3@PDI-Imidazole surface displayed significant enhancements in linear polarizability ( α0 = 706.472 au) and first hyperpolarizability ( β0 = 21314.360 au). It was observed by TD-DFT calculations that all the compounds had appreciable improvements in their interaction energies, HOMO–LUMO and UV–vis absorption and vertical ionization potential. Future development of nonlinear optical (NLO) devices has been discovered to benefit from the addition of OLi3 to the PDI-Imidazole surface.

Quantum computational and experimental spectroscopic investigation (FT-IR, Raman, UV–Vis), PES, LHE and topological investigations of 7-[(2R)-2-hydroxypropyl]-1,3-dimethylpurine-2,6-dione

The current research explored the structural optimization, electrical and vibrational characteristics, and quantum chemical calculations via the procedure of DFT for a purine derivative, 7-[(2R)-2-hydroxypropyl]-1,3-dimethylpurine-2,6-dione (2HDPD). Functional groups were found by correlating FT-IR with simulated spectra. TD-DFT calculations were done for UV–vis absorption and to ascertain the electronic properties of both the solvent and the gas phase, enabling additional study of the compounds LHE. The experimental outcomes and theoretic parameters are in good agreement. LUMO and HOMO band gaps spectacle that the molecule is chemically reactive and that there is adequate charge transfer. Polar solvent exhibits the highest band gap value, 5.057 eV. Numerous topological considerations were accomplished using the Multiwfn tool. Charge transfer investigations have demonstrated the most imperative states. Weak intermolecular interactions were investigated using RDG analysis, LOL, NBO, and ELF. The 2HDPD compounds reactive areas were discovered by applying the MEP and Fukui investigations. Hyperpolarizability characteristics were used to calculate NLO behavior. The drug-like characteristics of the molecule follow Lipinski five rules. After docking with the proteins 1NG2, 2DVV, 3CAF, and 7OEX, the compound 2HDPD showed moderate binding affinities of −5.28, −5.04, −4.96, and −5.66 kcal/mol, in that order. The Ramachandran plot verified the proteins stability and advantageous locations. The Docking results show compound 2HDPD exhibited a COPD property.

Silver(I) and gold(III) complexes with miconazole: The influence of the metal ion on the antimicrobial activity of the coordinated azole

To develop a new antimicrobial agent, we used the clinically approved antifungal azole, miconazole (mcz), as a ligand for the synthesis of silver(I) and gold(III) complexes. The new complexes [Ag(NO3-O)(mcz-N)2] (1) and [AuCl3(mcz-N)] (2) were synthesized and characterized by 1H NMR, IR and UV–Vis spectroscopy and mass spectrometry, while the crystal structure of 1 was determined by single-crystal X-ray diffraction analysis. From the results obtained, it can be concluded that in both complexes, mcz is monodentately coordinated to the silver(I) and gold(III) ions through the imidazole nitrogen atom N3. In the solid state, complex 1 contains two mcz ligands and monodentately coordinated nitrate in the third position, while in the case of 2 gold(III) ion is coordinated by one mcz and three chlorido ligands, resulting in the expected square-planar arrangement around the metal center. DFT and TDDFT calculations were employed to elucidate the electronic structures and thermodynamic stability of the synthesized complexes in solution to complement the experimental findings. The coordination of mcz to silver(I) and gold(III) ions leads to an enhancement of its activity against Gram-negative Escherichia coli and Pseudomonas aeruginosa strains, while against the panel of Staphylococcus aureus and Candida species, only 2 shows improved activity compared to mcz. Both complexes 1 and 2 were tested in vitro for their antimycobacterial activity against the strain Mycobacterium tuberculosis H37Rv and showed good growth inhibition with minimum inhibitory concentration (MIC) values of 3.12 and 8.69 μM, respectively, with complex 1 being twice effective as mcz (MIC = 7.50 μM). Complex 2 significantly reduced the production of pyocyanin, a virulence factor in P. aeruginosa controlled by quorum sensing, while this effect was not observed for 1.

Tuning the photophysical and NLO properties of β-diketonates derived from coumarin-triphenylamine-chalcones: effect of the BF2 group.

Herein the synthesis of three difluoroboron β-diketonate complexes (7a-c) and one chalcone (7d) with coumarin and triphenylamine fragments is described. The effect of the inclusion of the difluoroboron (BF2) group and a phenyl linker on the photophysical properties, intramolecular charge transfer (ICT) and nonlinear optical (NLO) properties was studied. These dyes exhibited excellent ICT properties due to their A-π-D and D-π-A-π-D type push-pull configuration. Thus, all compounds presented a strong solvatochromism, given the absorption and emission maxima shifted to red because of the increase in the polarity of the medium. In addition to this, 7a-d showed the formation of a twisted intramolecular charge transfer (TICT) state, which quenched fluorescence in polar solvents. Compounds 7a, 7b and 7d exhibited aggregation-induced emission (AIE) in MeCN/H2O mixtures, while 7c did not have this behavior. In addition, all compounds showed emission in the solid state. Using DFT and TD-DFT calculations, the molecular geometries of the ground state S0 and the first excited state S1 were elucidated, which confirmed the formation of a TICT state. Furthermore, the theoretical and experimental absorption electronic transitions were correlated by testing different functionals: B3LYP, CAM-B3LYP, PBE0, wB97XD, HSEH1PBE and M062X. Frontier molecular orbitals (FOMs) and molecular electrostatic potentials (MEPs) supported the ICT from the donor to the acceptor group. The global reactivity descriptors were studied and the NLO properties were predicted by calculating first (βtot) and second-order (γave) hyperpolarizabilities, revealing that 7a-d would present promising NLO behavior.

Highly efficient synthesis and photochromic properties of a pentacyclic N-heterocyclic carbonyl-based dithienylethene

Given that the photochromic functional materials possess outstanding phototropic color-change properties, the attention being paid to this field is progressively intensifying. The development of N-heterocyclic carbonyl photoswitching materials, harnessing dithienylethene site for photochromism, typically involves a complex multi-step synthesis process, which substrate diversification and the complexity of the preparation process are confronted with various challenges. Herein, we present a straightforward synthetic methodology for the preparation of photochromic 4,5-bis(2,5-dimethylthiophen-3-yl)-1,3-diphenyl-1,3-dihydro-2H-imidazol-2-one (1o) via reprogramming the synthesis pathway of dithienylethene-containing imidazolone using 1,3-diphenylurea. The current method demonstrates efficient reaction between α-hydroxy ketone and 1,3-diphenylurea in high yield, thereby enabling direct and straightforward one-step cyclization. The grown crystal sample of the targeted 1o has undergone single crystal X-ray diffraction analysis to elucidate its structural information. The ring-open (o-isomer) and ring-closed (c-isomer) forms showing remarkable fatigue resistance and high contrast visual color changes, can be effortlessly interconverted through the alternating irradiation of UV/vis light. To illustrate the electronic structure of the isomers, thorough analyses of the frontier molecular orbital based on TD-DFT calculations were conducted.

Suzuki-Miyaura coupling reaction: Blue-yellow emitting AIE active dyes for organic electronics

A series of eight novel donor‒acceptor (D─A) based 2,3-di(thiophen-2-yl)quinoxaline derivatives 2–9 were prepared by modulating donor species on quinoxaline core with Palladium catalyzed Suzuki–Miyaura ‘C–C bond’ coupling reaction. The synthesized molecules were fully characterized and studied for impact of D–A interaction on opto-electrochemical properties. Absorption spectra of 2–9 display intramolecular charge transfer (ICT) transitions in the range of 388–414 nm. Dyes shows positive solvatochromism and emit in blue‒yellow region with emission maxima 444−550 nm on excitation at their respective ICT maxima in toluene, chloroform, DCM, DMSO and neat solid film. Further, solid state emission was studied for aggregation‒induced emission (AIE) effect in THF–water system due to the nanoparticles formation, as confirmed by FEG‒SEM technique. The HOMO and LUMO energy level for compounds 2–9 were measured by cyclic voltammetry and found in the range of −5.15 to −5.94 eV and −2.81 to −3.39 eV. Theoretical studies of molecules were also carried out by using DFT and TD‒DFT calculations. The comparable HOMO and LUMO energy levels with reported ambipolar materials and efficient solid-state emission make synthesized compounds potential candidate for solid state emissive, ambipolar charge transporting materials in organic electronics.

Synthesis, spectral-fluorescence properties and TD-DFT calculations of 4-canotryptophan and its derivatives

Synthesis, spectral-fluorescence properties and TD-DFT calculations of 4-canotryptophan and its derivatives

Supramolecular hybrid of 4-aminopyridinium Perchlorate: Synthesis, molecular structure characterization, vibrational spectroscopy, thermal analysis, and optical property evaluation

A hybrid material, 4-aminopyridinium perchlorate salt [C5H6N2][C5H7N2] ClO4, was synthesized at room temperature by slow evaporation and characterized by single-crystal X-ray, spectroscopic techniques (FT-IR, Raman, and UV–Visible), thermal studies (TGA and DSC). The crystallographic data obtained from single crystal X-ray analysis showed that the compound adopts the monoclinic system, space group P21/n, with the following parameters a = 10.8317(8) Å, b = 9.0529(5) Å, c = 13.7032(9) Å, β = 99.243(3) °, Z = 4 and V = 1326.27(15) Å3. The stability of the supramolecular structure was ensured by hydrogen bonding contacts with N-H…O lengths ranging between 2.749 and 2.940 Å. According to the results of Hirshfeld analysis, O…H interactions constitute the main intermolecular interaction contacts (46 %). The thermal decomposition of the precursors, studied by TGA and DSC analysis, indicates that the compound exhibits thermal stability up to 130 °C, beyond which it degrades. Infrared and Raman spectra were recorded at room temperature, confirming the existence of vibrational modes corresponding to organic and inorganic groups. Additionally, the optical properties of the synthesized compound exhibit UV–Visible absorption and interesting photoluminescence properties. The related HOMO-LUMO orbital energies were also highlighted using TDDFT calculations the B3LYP/6-31G (d,p) level of theory.

Mer-M(CO)3(PNP)0/+ pincer complexes (M = W(0) or Re(I); PNP = 4,5-bis(diphenylphosphino)acridine): synthesis, spectroscopy and anti-Kasha emission.

Two isoelectronic and isostructural W(0) and Re(I) complexes mer-W(CO)3(PNP) (1) and [mer-Re(CO)3(PNP)]Cl (2) (PNP = 4,5-bis(diphenylphosphino)acridine) were synthesized and characterized by X-ray diffraction, infrared, electronic absorption and emission spectroscopy, and cyclic voltammetry. Structures of these complexes show a metal center bonded to the pincer ligand and two axial CO and one equatorial CO ligands. DFT calculations showed that the LUMOs of both complexes are the lowest energy π* orbitals localized in the acridine part of the ligand. The HOMO of 1 is dominated by the dπ orbital of W(0) while the HOMO of 2 has a substantial contribution from the highest energy π orbital of the acridine ring. TD-DFT calculations were performed to assist assignment of the UV-vis absorption spectra. The UV-vis absorption spectrum of 1 shows a very low energy W → π* (acridine) metal-to-ligand-charge-transfer (MLCT) absorption band that ranges from visible (500 nm) to near-infrared (>900 nm) regions and an intense acridine π → π* absorption band at 410 nm. There is a blue-green window in the ∼450-500 nm range between the π → π* and W → π*(acridine) MLCT absorptions. The absorption spectrum of 2, dominated by intense π → π* absorptions, shows no distinct low energy MLCT band. Complex 1 is luminescent, displaying acridine-based ππ* fluorescence at 501 nm which is anti-Kasha as it is higher in energy than the lowest energy excited state.