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The present work investigates on structural and chemical studies on 1-Phenyl Sulfonyl Pyrrole(1PSP) using quantum computational methods. The revamped geometric structure and its parameters were obtained through density functional theory (DFT). The electronic absorption transitions were discussed with different solvents were carried out by TD-DFT (Time Dependent Density Functional Theory) method. The IR intensities and Raman activites are tabulated for vibrational wavenunbers and its corresponding PED (Potential Energy Distribution) assignments in percentage were obtained from VEDA4 software. The inter and intra molecular interactions, electrophilic, nucleophilic and chemical reactivity sites are identified by Molecular electrostatic Potential (MEP), HOMO-LUMO (Highest Occupied Molecular Orbital and Lowest Unoccupied Molecular Orbital) and GCRD (Global chemical reactivity descriptors). Mulliken atomic charges were discussed with Natural Bond Orbital (NBO) analysis. Thermodynamic property and Non-linear optical deportment of the title compound is also talked about. Besides the electron localization function map, the density of states are also mapped with Multiwfn software, a wavefunction analyzer.

Dicarabrols B and C ( 1 and 2 ), two new carabrane sesquiterpenoid dimers, along with one new carabrane sesquiterpenoid ( 3 ) were isolated from the whole plant of Carpesium abrotanoides L. Their full structures were established by extensive analysis of HR-ESI-MS and NMR spectroscopic data, and time-dependent density functional theory (TDDFT) electronic circular dichroism (ECD) calculations. Dicarabrol B possesses a novel C30 skeleton featuring a methylene-tethered bridge between two sesquiterpene moieties, while dicarabrol C presents the unique linkage of a cyclopentane ring in the molecule. Dicarabrol C exhibited potent inhibitory effects on HL−60 cells with an IC50 value of 3.7 μmol·L−1.

Photocatalytic hydrogen production, capable of dissociating water to make hydrogen using sunlight as abundant and clean energy, provides a promising solution for energy crisis. However, currently dominated metal complexes photosensitizers are based on precious and rare metal elements, which prohibits large scale applications. Herein, based on the experimental dye Eosin Y (EY2−), we report a series of metal-free organic dyes EY2-1- EY2-18 and present a systematic study on their ground-state geometry, electrochemistry, energy gap, reduction potential and driving force by using density functional theory (DFT) and time-dependent DFT (TDDFT). The calculated results show that compared to other dyes, the dye EY2-11 has a large visible light absorption range, a higher reduction potential and greater driving force, which indicates that EY2-11 is a promising candidate for the visible-light-driven hydrogen production. Our theoretical researches are expected to provide valuable insights for designing efficient metal-free organic photosensitizers.

A series of D-A-π-A organic dyes are taken into consideration to study the influence of different internal acceptor groups and thiophene based π-spacers on their efficiency in dye-sensitized solar cells (DSSCs). Density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods are used for investigating the electronic excitations along with their geometrical and charge transport properties. HOMO, LUMO energy levels and HOMO-LUMO energy gap helped in the understanding of energy levels appropriate for electron injection, electron transfer and dye regeneration. Thereafter, the calculations for short circuit current density (JSC) were performed by considering injection driving force (ΔGinj), dye regeneration energy (ΔGreg) and light-harvesting efficiency (LHE). In addition to this, charge transport properties like electron reorganization energy (λe), hole reorganization energy (λh), electron affinity (EA) and ionization potential (IP) are also reported. The results show that the insertion of internal acceptor in D-π-A system and variation in the length of π-spacer results in red-shifted absorption along with improved photovoltaic properties. Hence, the main purpose of this present study is to provide a theoretical background for proper designing and structural modifications in the development of efficient dyes in dye-sensitized solar cells (DSSCs).

In this study we report the results of first principle quantum chemical modeling of electronic structure and spatial configuration of LaF3 crystal containing the F-center. Theoretical predictions of atomic and electronic properties of LaF3 are given by means of density functional theory. From our modeling we predict that the F-center placed at fluorine ion position between the lanthanum planes at tysonite LaF3 is the most energetically stable. In order to interpret the structure of the optical absorption spectrum of X-irradiated LaF3 we performed calculations of excited and transition states of the F-center within the embedded cluster formalism using time dependent density functional theory. Predicted transition energies and oscillator strengths of LaF3 containing the F-center are in line with those recently measured.

(±)-Crataegusnorin A (1a/1b) and B (2a/2b), two pairs of rare 8,9′-epoxy-type norlignan enantiomers featuring a γ-butyrolactone ring, were isolated from the fruit of Crataegus pinnatifida. Their structures were determined via extensive spectroscopic analyses. Gauge-independent atomic orbital (GIAO) NMR chemical shift calculations, combined with the advanced statistical method DP4+ were employed to establish the relative configurations of four compounds. Next, chiral separation was accomplished by chiral chromatographic column and the absolute configurations of the four compounds were unambiguously assigned by comparison between their experimental electronic circular dichroism curves with the quantum-mechanically calculated curves based on time-dependent density functional theory (TDDFT). All the isolates were evaluated for their neuroprotective activities against H2O2-induced cell injury in human neuroblastoma SH-SY5Y cells. The results showed that two pairs of enantiomers 1a/1b and 2a/2b displayed diff ;erent effect on neuroprotective activity. Among them, compound 2a displayed the most potent neuroprotective effect. Further flow cytometry analysis indicated that 2a could protect SH-SY5Y cells from oxidative damage through inhibiting cell apoptosis.

In this paper, we applied the two methods: DFT and TDDFT to study the structural, electronic and optical properties of the inorganic solar perovskite KPbBr3. To reach this goal, we performed the DFT method under the Quantum Espresso package. The total energy of the cubic perovskites KPbBr3 has been calculated as a function of the lattice parameter a (A). The two calculation methods have been carried out under the approximations: GGA-PBE and GGA-PBESol. In addition, the total and partial density of states (DOS) and the band structure of the studied compounds have been illustrated and discussed for the two cases in the presence or in the absence of the spin orbit coupling (SOC) approximation. The density functional theory (DFT) and time-dependent density-functional theory (TDDFT) have been explored in order to elaborate the optical properties of the inorganic solar perovskite KPbBr3 for solar cell applications. The band gap energy value found when applying the GGA-PBESol method without SOC approximation, is greater than that one computed when taking into account the SOC correction. Moreover, the optical properties of the studied materials have been elaborated and discussed.

The significance of five membered heterocycles in simple donor-acceptor system was elaboratively studied by density functional theory (DFT) and time dependent density functional theory (TDDFT). By effectively substituting eight different rings the HOMO-LUMO gap can be reduced considerably. The nuclear independent chemical shift (NICS) calculations help to predict the aromaticity of central heterocyclic systems. The natural bond orbital (NBO) analysis reveals the charge contribution. The close observation of frontier molecular orbitals (FMO) gives a detailed explanation of delocalization.

Modeling of cationic and excited states of boron difluoride acetylacetonate and eight of its γ-substituted derivatives was carried out using the methods of outer-valence Green's functions (OVGF), algebraic-diagrammatic construction for the polarization propagator of the second order (ADC(2)), coupled clusters with single and double excitations (EOM-CCSD), and time-dependent density functional theory (TDDFT/CAMB3LYP). Comparison of the calculated data with the absorption spectra made it possible to determine the influence of functional groups on the energies of electronic transitions and the nature of the absorption spectrum bands. Addition of the substituent SPh causes a decrease in the energy gap between the levels of the highest occupied and lowest vacant molecular orbitals, which determine the bathochromic shift of the long-wavelength band in the absorption spectrum relative to the other studied complexes. In the complexes containing Cl, Br, SCN, SEt, SPh and OS(O)2Ph groups in the γ-position, it was found that the highest occupied molecular orbitals are localized mainly on the substituents, and the lowest vacant molecular orbital corresponds to the chelate orbital π4, which determines the presence of transitions with charge transfer. It was shown that the calculated energies of excited states according to the ADC(2) method, in comparison with EOM-CCSD and TDDFT/CAMB3LYP, can be correlated with maxima of the experimental absorption spectra for the lowest average shift (0.27 eV).

The ground (S(0)) and excited triplet (T(1)) electronic states and corresponding optical spectra of a series of cationic complexes [RuH(CO)L(PPh(3))(2)](+) (L=2,2´-bipyridyl) (Rubpy), 4,4´-dicarboxylic-2,2´-bipyridyl (Rudcbpy), bis-4,4’-(N-methylamide)-2,2´-bipyridyl (Rudamidebpy), bis-4,4’-(methyl)-2,2´-bipyridyl (RudMebpy), [Ru(CO)(2)dcbpy(PPh(3))(2)](2+) (Ru(2CO)dcbpy), and [Ru(H)(2)dcbpy(PPh(3))(2)] (Ru(2H)dcbpy) have been studied by combined Density Functional/Time-Dependent Density Functional (DFT/TDDFT) techniques using different combinations of DFT exchange-correlation functionals and basis sets. PBE0/LANL2DZ provided more accurate geometries to describe S(0) whereas B3LYP/LANL2DZ predicted spectral energies that correlated better with the available experiment data. The Ru (II) complexes with different substituents emit photons ranging from 560–610 nm in the series RudMebpy, Rubpy, Rudamidebpy, Rudcbpy. The calculations predicted a maximum emission at about 540 nm for the complex constructed from two carbonyl π-acceptors ligands trans to the dcbpy, while an emission in the far infrared region is calculated when two H σ-donor ligands trans to the dcbpy. Our calculation results show correlations between HOMO-LUMO energy gap, Stokes shift, and T(1) distortion, which reflect the different effects of electron-withdrawing and donating groups. We proposed that these correlations can be used to predict the photophysical properties for new complexes.

We propose a three-dimensional time-dependent density functional theory (TDDFT) to investigate the freezing/melting of Lennard-Jones fluids in interfacial systems including flat interfaces and nano-droplets. The theory is based on a modified fundamental measure theory (MFMT) for the hard-sphere reference system plus mean field theory (MFT) for the attractive contributions plus an additional weighted density approximation (WDA) contribution to enforce that bulk liquid equation of state is that of modified Benedict, Webb and Rubin (MBWR). By using different initial states, our theory generated a series of equilibrium structures including crystals and polyhedral particles. The non-linear effect and the irreversibility of the freezing/melting process were captured. The profiles for free energy and the order parameter indicate that the free energy barrier existing in the freezing/melting process is caused by the break in symmetry. Additionally, the time-dependent properties were also examined, and provided insight into the mechanism of the freezing process.

The metal free organic sensitizers for dye sensitized solar cells (DSSC) have been developed from carbazole donor based on D-π-A architecture. From the structural modifications, the optical and electronic properties of the dyes were tuned. In the present investigation series of carbazole donor based metal free dyes were studied using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The optimized geometry, frontier molecular orbitals, energy levels and electronic absorption spectra were studied. The natural bond orbital analysis (NBO) gives the net electron transfer from the donor to acceptor. The electrochemical properties and light harvesting efficiency of the designed dye sensitizers were calculated. The π spacer increase induced the absorption peak and red shift was noted. The life time was increased by adding phenyl ring in the donor side. Based on theoretical calculations designed dye molecules are evaluated for DSSC application.

Because of the importance and growing application of chemical sensors, mechanism of Nʹ-((8-hydroxy-1,2,3,5,6,7-hexahydropyrido [3,2,1-ij]quinolin-9-yl)methylene)benzohydrazide (NHH) ligand activity to detect Al3+ cation in water solvent through DFT and TD-DFT methods was studied here. DFT calculations were conducted using the B3LYP function whilst TDDFT calculations were performed by using the CAM-B3LYP function and considering the solvent effect. Ground state charge transfer was calculated using the NBO analysis and the DOS graph of ligand and the complex were also obtained. The calculations on the UV–Vis absorption spectra and the fluorescence emission indicate that the emitted spectra showed a considerable Red-Shift after the complex being formed. The reason of such change was about the geometry of the ligand after the formation of the [Al·NHH]3+ complex. The phenomenon of photo-induced electron transfer and photo-induced charge transfer were studied using the theory of hole-electron and it was revealed that the reason for increase of the emitted wavelength was about a PET cut off (break) after formation of a complex in three states of excitation, with absorbing wavelength of 272.33, 248.54 and 235.91 nm, toward fluorophore, respectively.

A mononuclear Cu(II) complex [CuII(L)](1) [H2L=N,N′-bis(2-hydroxy-3,5-di tertiarybutylbenzyl)-homopiperazine] has been synthesized by using sterically constrained tetradentate phenol-based ligand. Characterization of this compound has been carried out by various spectroscopic tools. Compound 1 crystallizes in orthorhombic space group P212121 with a = 9.9794 A, b = 11.944 A, c = 28.719 A. Single crystal X-ray diffraction study reveals that in mono nuclear copper(II) complex [CuII(L) ] 1, the metal center adopts a square planar environment. The geometry of the Cu(II) complex has been optimized using density functional theory (DFT) calculations. Electronic excitation energies of the above mentioned complex are calculated by TDDFT/UB3LYP method combined with the SMD solvation in methanol medium. Electrochemical nature of the bis phenol based copper complex confirms that both the oxidation process (E1/2 = 0.56 V and E1/2 = 0.89 V) arise due to ligand based oxidation of the phenol moiety to phenoxyl radical. Compound 1 acts as an effective catalyst towards the oxidation of 3,5-di-tert-butylcatechol in methanol solvent to its corresponding quinone derivative in aerial oxygen. The kinetic parameters have been determined using Michaelis–Menten approach. The Kcat value for 1 in methanol is 722 h−1.

Using TDDFT method, modulating mechanism of N H-based excited-state intramolecular proton transfer by electron-withdrawing substituent cyano at the aromatic para-position of four 2-(2′-aminophenyl) benzothiazole compounds have been demonstrated at B3LYP/6-311+G(d, p)/IEFPCM theory level. The scanned potential energy curves reveal that introduction of a strong electron-withdrawing group tosyl at the amino nitrogen can remarkably facilitate the occurrence of the ESIPT reaction, whereas introduction of a weak electron-withdrawing group acetyl at the amino nitrogen or introduction of an electron-withdrawing cyano group on the benzene ring at the para-position with respect to the amino group can contribute to the ESIPT process in certain degree.

Graphitic carbon nitride (g-C3N4), an environment-friendly metal-free photocatalysts represent a promising alternative to conventional metal-based semiconductors. Although sp2-structured carbon-dot modified g-C3N4 has shown its effectiveness to enhance the photocatalytic efficiencies, a precise, comprehensive and molecular level understanding of this enhancement is demanded for advance progress, which is lacking due to the complexity of the samples in experiments. Here, our density functional theory (DFT) and time-dependent DFT calculations reveal that a precise graphene quantum dot (GQD) sensitization of g-C3N4 nanosheet significantly enhance excited-state charge separation, which is crucial for the photocatalytic activity. Nitrogen to carbon ratio is critical for the spatial separation of photogenerated electron-hole pair via GQD/g-C3N4 π-π stacking. Red-shift in the lowest excitation of GQD/g-C3N4 with size increment stretches the absorption to the visible wavelengths, facilitating the visible-light photocatalytic activity of g-C3N4. The mechanism revealed in this study supports the recent experimental reports on the competence of the environmental friendly, low cost and stable GQD sensitized g-C3N4 photocatalyst and provides guidance for optimal design to achieve higher efficiency.

Three new coordination polymers (CPs), [Ag(MTP)2(PF6)]n 1, [Ag(MTP)(NO3)]n 2 and [Ag(MTP)(OTf)]n 3 (where MTP = 2-(Methylthio)Pyrazine and OTf = CF3SO3−) have been synthesized and characterized by different spectroscopic techniques. The single crystal X-ray study reveals that CPs 1 and 2 are two dimensional, whereas 3 is three dimensional. In the case of CP 1, MTP has two types of bonding behaviour. In one it is coordinated through the nitrogen of pyrazine only, leaving sulfur of –SMe free, whereas, in the other, it bonded through both sulfur and nitrogen of MTP. The sulfur of –SMe is coordinated to the neighbouring [Ag(MTP)]n chain in 2 whereas, in case of 3, sulfur of –SMe remain uncoordinated. Absorption and emission spectra of MTP and CPs have been studied in solution state. The spectral behaviour was supported by time dependent density functional theory. The emission behaviour of CPs in the presence of different metal ions confirms that only CP 1 has some affinity towards Hg(II) and Cu(II) ions.

Phenothiazine (PTZ) derivatives represent an important class of molecules, being studied in a number of fields of chemical and pharmaceutical research. The interesting chemical and biological properties of PTZs are considered to be related to their relative stable radical cations, whose formation and reactivity have been extensively studied. In this work, the radical cation of phenothiazine (PTZ+) was generated by the reaction with the mordenite solid acid, an environment in which this species is stabilized. The most intense electronic transition of PTZ+ is located at 516 nm. In order to characterize the electronic and molecular structure of this radical species, a resonance Raman and theoretical calculations of the structure, PTZ+ vibrational frequencies and electronic spectrum were calculated employing DFT B3LYP/6-31G(d,p) and TDDFT methods. In the ground state, PTZ+ is planar, in contrast to the folded structure of neutral PTZ. The strong Raman band at 476 cm−1 was assigned to a CSC bending mode. The reason for its preferential enhancement was investigated using TDDFT, in order to obtain the molecular orbitals involved in the electronic transition at 516 nm. The TDDFT calculations show that this transition is from SOMO-1 and SOMO-2, both double occupied molecular orbitals, localized at the aromatic rings and goes toward SOMO (single occupied molecular orbital). This SOMO has contributions of sulphur and nitrogen atomic orbitals, but with predominance of sulphur atomic orbitals, which are absent in SOMO-1 and SOMO-2. The predominance of sulphur atomic orbitals in the SOMO explains the preferential resonance Raman enhancement of a CSC vibrational mode.

Fully-inorganic perovskite quantum dots (QDs) have emerged as an exciting family of semiconductor materials with outstanding opto-electronic properties. Here, using state-of-the-art time dependent density functional theory calculations, we present a comprehensive study of the absorption cross-sections and the electric field enhancements of fully-inorganic off-stoichiometric APbX3 (A = Rb, Cs and X = Cl, Br, I) perovskite QDs. We show that the type of halide element is a key parameter in determining the QD optical features. Specifically, we demonstrate the dramatic variations in the electric field enhancements and the significant modifications in the hotspot regions with respect to the halide element, confirming the excellent photo-catalytic activity of perovskite QDs reported by the recent experiments.

Hybrid organic-inorganic metal perovskites (ABX3, A- organic cation, B-metal ion, X-halide ion) have shown significant potential as thin-film solar cells or Dye solar cells (DSC) materials. Using a time-dependent density functional theory (TDDFT) study, this work explores the role that the central organic cation plays in defining the optoelectronic and physical properties of metal perovskites. Cubic phases of CH3NH3PbI3, CH3NH3PbCl3, CH3NH3PbICl2, and CH3NH3PbI2Cl perovskite structures are investigated using TDDFT with Gaussian 16. Electronic and optical properties, including transition energy, band gap, IR and absorption spectra and vibrational frequencies are examined. It is observed that the organic cation reduces the unit cell volume of the outer metal halide structure from approximately 9–20% for different perovskite materials. The peak optical absorption also correspondingly decreases by a significant margin, ranging from about 40–60%. This work is partially supported by the United States Office of Naval Research through grant number N00014-18-1-2732 . Scopus

The development of novel anchoring groups is important for the effective utilization in dye-sensitized solar cells (DSSC). Among metal complex sensitizer, Pt(II) diimine dithiolate (PtN2S2) complexes have been proposed as alternative sensitizers owing to their ultimate photophysical and photochemical properties. Herein, a series of [Pt(bpy)(bdt)] sensitizers with different anchoring groups on the bpy (diimine) ligand have been designed and their geometrical, electronic, and photophysical properties for DSSC applications have been systematically examined both in the presence and absence of a solvent using density functional theory (DFT) and time dependent density functional theory (TD-DFT) methods. A precise electronic structure is also presented on the basis of NBO analysis. The seven anchoring groups are considered including aldehyde (1), hydroxamate (2), cyanoacrylic acid (3), carboxylic acids (4a−4c), boronic acid (5), phosphonic acids (6a−6c), and sulfonic acid (7) substituents. The results indicate that the gap energy (HLG) and electrophilicity (ω) values obtained for these structures alter by anchor addition. Notably, the anchors 1 and 7 have remarkable effect on the electronic features of [Pt(bpy)(bdt)] sensitizer. From the TD-DFT calculations, it is found that the substitution of the considered anchoring groups enhances the intensity of the absorption and the overall absorption spectrum can be red shifted significantly by lowering the LUMO energy. Besides, the values of light-harvesting efficiency (LHE) have calculated and compared with each other. These findings highlight the importance of using anchors 1 and 7 to boost the LHE of DSSCs. Thus, our results may give a useful guidance for the molecular design of the metal complex sensitizers used in DSSCs.

Organic photovoltaic (OPV) solar cells recently achieved a reported efficiency as high as 17.3%. In this study we explore new avenues of shifting the light absorber through rational design of the π-spacers in the Donor–π-spacer–Acceptor dyes. That is, to construct high performing new dyes with fixed donor (DCPA) and acceptor (PMID) from appropriate π-building units of fluorene, EDOT and thiophene. These three π-units form various combinations of the π-conjugate spacers for new dyes. We focus on the development of the relationship between the three building units of π-spacers to construct new DCPA–π-spacer–PMID dyes and their UV–vis spectra in tetrahydrofuran (THF) solution. The latter (i.e., UV–vis spectra) are calculated using quantum mechanical time dependent density functional theory (TD-DFT) methods. This set of nine new organic dyes has been employed to develop augmented intelligence (AI). We discovered that repeating the fluorene (πO) unit alone in the π-spacer, such as OP100, OP200 and OP300 dyes, will lead to hyperchromic enhancement of the donor spectral band in the UV region of ca. 300 nm, with limited impact on the major spectral band at 500 nm which is stemmed from the acceptor (PMID). To maximize the UV–vis absorption, more efficient π-spacers for this class of dyes are constructed from mixtures of the fluorene (πO) and EDOT (πP) units, such as πO-πP-πO (OP210) or as πO-πP-πO-πP (OP220). The information obtained is useful to elucidate new dyes with desired properties with appropriate UV–vis spectra for future machine learning (ML).

2-(4-(Dimethylamino)phenyl)-3-hydroxy-6,7-dimethoxy-4Hchromen-4-one (HOF) was synthesized in experiment (Wang et al., Sensor. Actuat. B-Chem. 277 (2018) 484), and its photophysical and photochemical properties was reported. However the corresponding full theoretical interpretation of mechanisms is inadequate. In the present research, the intermolecular hydrogen bond structure of HOF-methanol complex (HOF-2M) was found, and mechanism of alcohols monitoring of HOF was deeply studied using the density functional theory (DFT) and time-dependent density functional theory (TDDFT). The enhancing mechanism of the excited state hydrogen bond is verified by analyzing the hydrogen bond parameters, infrared spectra and frontier molecular orbitals. Importantly, the reduced density gradient visual analysis and topological quantificational analysis confirm that the intramolecular hydrogen bond of HOF is broken by strong intermolecular hydrogen bonds of HOF-2M using the Atoms-In-Molecule theory. The obtained absorption and emission spectra are found to agree well with the experimental results and the complete quenched keto-emission in methanol and ethanol solvents provide a suitable sensing mechanism for detecting alcohols. The reaction path of the excited state intramolecular proton transfer for HOF is explained in detail through the constructed potential energy curves.

In perovskite solar cells (PSCs), the hole extraction/transport and the device stability are strongly dependent on the molecular structure of the hole transporting material (HTM). Designing of organic HTMs that are efficient for charge extraction and transport when integrated into optoelectronic devices is of great importance. The two fabricated devices: TiO2/CH3NH3PbI3/PYOMe/Au and TiO2/CH3NH3PbI3/spiro-OMeTAD/Au PSCs, where the HTMs in the two devices are a pyrene-core N1,N1,N3,N3,N6,N6,N8,N8-octakis(4-methoxyphenyl)pyrene-1,3,6,8-tetraamine (PYOMe) and the classical spiro-OMeTAD, respectively, recorded very comparable performance. The overall power conversion efficiencies are 12.4 and 12.7%, respectively. However, the preparation of PYOMe is more cost-effective, and it is predicted that the PY-core compounds will have faster charge-transport ability compared to the spirobifluorene core. Herein, we have engineered a PY-core compound (PYOMe) with groups of different electron-donating abilities at the para-position. DFT/M06/6-311G(d,p) and TDDFT/M06/6-31G(d) levels were used to investigate the geometrical, electronic and optical properties of these derivatives in their neutral, cationic and anionic forms. The frontier orbital energy levels and their spatial distribution were computed for all derivatives and compared in the neutral and ionic forms. The results indicated that groups with different electron-donating abilities in the PY-core framework lead to different optical properties. According to the calculations, stronger electron-donating substituents remarkably destabilize the HOMO and LUMO, while weaker electron-donating substituents stabilize them. The reorganization energy, electron affinity, and ionization potential were also calculated and discussed. Finally, to shed light on the intrinsic mobility, the charge transport properties of three HTMs as representative examples were calculated and analyzed.

The precise understanding of the exciton dynamics of technologically relevant organic systems is important for a plethora of applications, including solar energy conversion. Using state-of-the-art quantum chemical calculations based on time dependent density functional theory, we investigate the exciton dynamics of both the pristine and zinc (Zn) intercalated pentacene dimers as a function of the inter-molecular distances. We elucidate that the key difference in the exciton dynamics of pristine (Zn intercalated) pentacene dimers is that in the former (latter) the exciton size increases (decreases) with the increasing inter-molecule distances. Importantly, Zn intercalation causes increasing overlap between the electron and hole states and enhances the generation of low-energy charge-transfer excitons. We believe that our theoretical results are important for the emerging field of organic materials for solar-based applications.

Radiation is energy travelling through space. Sunlight radiation such as ultraviolet (UV) radiation are higher-energy radiation which are used in medicine and energy industry such as dye sensitized solar cells (DSSCs). We recently designed new Ru-complexes through novel ligands based on a recently synthesised high performance dye, i.e. [(η6-p-cymene)Ru(4,4′,5,5′-H4tcbpy)Cl]Cl [1] (A as L1-Ru-L2) for applications in DSSCs. Two electron rich top-ligands, η6-N, N, N′, N′-tetramethyl-p-phenylenediamine (new dye D) and η6- 1,4 di[(dimethylamino)ethyl] benzene (new dye E) outperform other ligands for the new high performance Ru-complexes. Our time dependent density functional theory (TD-DFT) using the CAM-B3LYP/6-311G+(d)/LANL2DZ functional and basis-set model reveals the apparent enhancement of the major UV–vis bands of metal to ligand charge transfer (MLCT) in the new dyes. The major UV–vis bands of the new dyes D and E are red shifted 35 nm and 78 nm, respectively, from the MLCT band of the reference dye A centred at 433 nm. We further discovered that the electron rich top-ligands (L1) are responsible to lift a cluster of occupied outer valence orbitals such as HOMO, HOMO-1 and HOMO-2 in the new D and E complexes, while the virtual orbitals which concentrate on the lower ligand L2 (4,4′,5,5′ H4 tcbpy) remain almost unchanged. The top-ligand L1 enhances the MLCT transition of the new dyes D and E through the dominant 7dz2 electrons of the transition metal Ru in their HOMOs. The present study provides the rational of ligand control for metal complexes in broader applications such as electron transfer and electronics.

Herein, we synthesized a red-emitting fluorescence turn-on probe (HSA) for specific detection of cysteine (Cys) over other biothiols (glutathione (GSH) and homocysteine (Hcy)). The acrylate group was chosen as the recognition site for specific discrimination of Cys. Absorption and emission spectra display a high selectivity towards Cys over GSH/Hcy, organic small-molecule interfering substances and anions, with a high sensitivity towards Cys (0.12 μM) in 1% ethanol-containing PBS buffer solution (25 mM, pH = 7.4). Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations were conducted to clarify the luminescence mechanism of the probe. Furthermore, the probe was successfully applied to the determination of free Cys in human serum and the fluorescence imaging of endogenous Cys in living cells.

The PDCBT shows much better performance than P3HT in non-fullerene organic solar cell although the former only replaces hexyl by alkoxycarbonyl group compared with the latter. In this work, we will focus on this tiny difference in structure and huge difference in performance between these two polymers from theoretical perspective. Thus we present a comparative study based on the dependent/time-dependent density functional theory (DFT/TDDFT) calculations and molecular dynamic (MD) simulations. The results reveal that PDCBT not only possesses lower molecular orbital energy levels which leads to the increasement of the open circuit voltage (VOC), but also exhibits better planarity and larger hole mobility than P3HT. In particular, comparing with P3HT system, PDCBT system also displays the higher charge separation rate and smaller charge recombination rate both in hole transfer and electron transfer process at the interface, which promote the enhancement of short-circuit current density. Therefore, this work provides a fundamental understanding of the prominent influence of the replacement of hexyl group by alkoxycarbonyl in P3HT on the cell performance and also provides some theoretical guidance for further optimization of donor materials in non-fullerene organic solar cells (OSCs).

In the present study, ethyl-2-(2-(2-methylbenzylidene)hydrazinyl)thiazole-4-carboxylate (1) and ethyl-2-(2-(4-bromobenzylidene)hydrazinyl)thiazole-4-carboxylate (2) were synthesized. The characterization of synthesized compounds was accomplished by employing analytical techniques of spectroscopy as 1H NMR, 13C NMR, FT-IR, UV–Vis and final confirmation was furnished using single crystal X-ray diffraction (SC-XRD) technique. The informations regarding optimized geometry, nonlinear optical (NLO) properties and frontier molecular orbitals (FMOs) were obtained by applying B3LYP level of DFT and 6-311 + G(d,p) basis set. As a whole, the computed results from DFT were found in close agreement to that of experimental results. The combination of B3LYP level of time dependent DFT (TDDFT) and 6-311 + G (d,p) basis set were employed for computational calculations of vertical electronic transition states. The stability on account of hyperconjugation and charge delocalization factors was evaluated through the study of natural bond orbitals (NBO). The capabilities of the title compounds with respect to charge transfer and involvement of various sites in chemical activities were evaluated quantitatively by employing the analysis involving frontier molecular orbitals (FMOs). The studies revealed that the compounds possess sizable NLO character as the NLO properties of urea molecule were found smaller as compared to the compounds under investigation which means that such compounds are significant in perspective of technology applications.

1, 1, 2-Trimethyl-1H-benzo[e]indole based D-π-A type semisquaraines denoted as, SSK 1–3 were synthesized to investigate their primary photophysical properties, intramolecular charge transfer, solvatochromism, electrochemical properties and viscosity dependent enhanced emission. These semisquaraines contain 1, 1, 2-trimethyl-1H-benzo[e]indole and squaryl ring as donor and acceptor respectively. These dyes displayed absorption between 437 and 444 nm and emission in the range of 469–493 nm. Stokes shift of the synthesized compounds were in the range of 32–54 nm. The SSK 1–3 exhibited intense yellow-orange colored solid state fluorescence (Fmax = 520–549 nm). These dyes exhibited intramolecular charge transfer characteristics which were confirmed from their oscillator strengths, transition dipole moments, ground and excited state dipole moments and generalized Mulliken-Hash analysis (GMH). Moreover, the positive emission solvatochromic behaviour (Δλem = 21–24 nm) of these dyes was quantitatively analyzed from different solvent polarity plots. More interestingly, these D-π-A type FMRs displayed viscosity sensitive emission enhancement (23 to 32 fold increase in fluorescence intensity) in 99% methanol:glycerol system at the visible region of electromagnetic spectrum (450–650 nm). The molecular structures of SSK 1–3 were correlated with photophysical properties using density functional theory (DFT) and theoretical absorption spectra in eight different solvents were obtained from time dependent density functional theory (TD-DFT).

Tetraphenylporphyrin (TPP) has been reported as the sensitizer of the dye-sensitized solar cells (DSSC). However, the efficiency is unsatisfactory because of the unobvious visible light absorption. Here we examine the improvement of the efficiency by using a sensitizer of cir-coronene graphene oxide quantum dot (GOQD) and TPP composite. The geometrical structures of the GOQD-TPP nanocomposites, as well as their separate components, are fully optimized by employing the first-principles density functional theory (DFT). The frequency analysis is used to confirm the energy stability of the obtained structures and time-dependent DFT (TDDFT) is used for the calculations of the optical absorption. We use the I−/I3− electrolyte, and the conduction band minimum of TiO2 electrode as the example to examine the feasibility of the nanocomposites as the sensitizer of DSSC by evaluating the energy levels, the charge spatial separation of the frontier molecular orbitals and electron transfer of the nanocomposites. The results demonstrate that the GOQD(18OH)-TPP can meet the necessary conditions of the sensitizer of DSSC. Besides, the most favorable is because of its larger driving force and light-harvesting efficiency, the suitable open-circuit voltage value, and enhancement light absorption. The results implicate that this one is the most promising sensitizer candidate of DSSC. These findings can provide a useful reference for developing the sensitizer of DSSC or designing the materials to harvest solar energy based on the nanocomposites of GOQD-TPP.

A molecule fluorescence probe of a new ON-OFF type, used for detecting transition metal ions, reported recently, is self-assembled by thiacalix[4]arene(TCA) molecules, micelles and a fluorescence group. It only presents high selectivity for Cu2+ ions, in a solution with the coexistence of Zn2+, Ni2+, Hg2+, Cu2+ Cd2+ ions. Since the mechanism of the ON-OFF signal response of such self-assembled micelle probes has always been a controversial issue of uncertainty, the mechanisms of the signal response and the high selectivity for Cu2+ ions were studied here by DFT/TDDFT method. The spatial arrangement, geometric and electronic structures of the functional units of the probe were calculated, and the response mechanism was investigated by the molecular transition orbital pairs method to explore the origination of the ON-OFF fluorescence signal response. The results told that the signal response process was based on forster resonance energy transfer (FRET) mechanism. The high selectivity for Cu2+ ions was due to the unique electron configuration of the copper complex, by the comparing of the calculation results of the TCA complexes M1-4(TCA)(M = Cu, Hg, Ni). The results provided new sights different from most of the conclusions by the related research works reported.

The density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations were performed to get insights into the properties of PRODAN derivative in toluene at both ground as well as excited states. On the basis of molecular structure analysis, spectra comparisons and electron density studies, we confirm that the intermolecular hydrogen bond in PRODAN derivative-toluene complex is strengthened upon the photoexcitation. Frontier molecular orbitals exhibited the similar electron density distributions in HOMO and LUMO, suggesting that the PRODAN derivative 1a experiences the local excitations in toluene.

In the present study, twenty three new vinyl coupled furan oligomers (VCFOs) and four already reported thiophene oligomer (VCTOs) have been investigated for potential optoelectronic properties using DFT/TDDFT calculations. Frontier molecular orbital analysis shows that the HOMO-LUMO gap of VCFO7b is the lowest among all the candidates while VCFO1a bears the highest HOMO-LUMO gap. The VCFOs display high NLO activity, exergonic type electron injection characteristics and VCTO1&3 have low NLO activity & endergonic type electron injection characteristics. Furthermore, the study investigates the influence of heterocyclic unit in HOMO-LUMO gap, NLO activity, exciton binding energy, light harvesting efficiency, electron injection properties in VCFOs& VCTOs. As a whole 21 out of 23 designed VCFOs are found to have remarkable optoelectronic properties compared to their corresponding VCTOs. Overall, our results suggest that furan oligomer tunes the optoelectronic properties to a great extent than the thiophene oligomers.

Recently reported diphenylamine (DPA) in conjugation with biphenyl based D-π acceptor-D type mixed valence compounds (MV) have paved the way to design and development of new set of mixed valence compounds. In the present work, heteroaromatic π-acceptors (bi-furan, bi-thiophene and bi-pyrrole) have been used to design eight new molecules and their optoelectronic properties have been evaluated using density functional theory (DFT) calculations and compared with their biphenyl derivatives. Frontier molecular orbital analysis has been carried out to gain insights into role of different groups towards the HOMO and LUMO of the molecule. Optoelectronic properties such as absorption and emission spectra of DPA (neutral) molecules, mono- and di- cation spectra of all the DPA derivatives have been probed through time dependant density functional theory (TDDFT) calculations. All the newly studied MV compounds have a good electron delocalization, electron coupling constant and high redox potentials than their reported biphenyl derivatives. Furthermore, the study highlights a fine correlation between the computed optoelectronic properties and HOMO-LUMO energy gap, which portrays the role of hetero aromatic π-acceptors on the photo-physical properties of DPA derivatives.

Monascus pigments (MPs) as natural food pigments which have been extensively used in food industries, specifically in China, Japan, and other countries of southeastern Asian. The optoelectronic properties of the MPs with polycyclic aromatic hydrocarbons (PAHs) units have been investigated by using density functional theory (DFT) and time-dependent (TDDFT) at B3LYP and the 6-31G(d) basis set. These properties include total energies, Fermi energy, work function, orbital distributions (HOMO, LUMO), the HOMO-LUMO gap, the maximum open circuit voltage, maximum wavelength absorption, electronic transition energies, and the oscillator strengths. These methods and calculation procedures not only encourage a profound understanding of the association between the optoelectronic properties and chemical structures of the molecules but also can be utilized to design new molecule structures. We investigated the influence of the PAHs into the MPs and studied the optoelectronic properties on all molecules. The results showed that the maximum absorption wavelengths for MPs-PAHs are within the visible light region. Therefore, these molecules provide good performance for the photovoltaic devices and solar cells applications. Significance Our results showed that the total energy increase after addition of PAHs for MPs, this illustration that the molecules converted to more stability. The addition of PAHs can enhance HOMO, LUMO level which can upsurge reduce bandgap energy and also the faculty of electron injection. Where the bandgap energy lies in the range (2.242–3.012) eV. The λmax takes the values from 378.84 nm to 681.03 nm, where the lowest value for Ms. (S3) and highest for the Ms. (S1), where Ms. (S1) represents firsa t singlet excited state that is at about 681.03 nm but with a feeble absorption. We observed that the sturdy absorption peaks (Ms (S2), Ms-fluorene (S3), Ms-naphthalene (S3), and Ms-anthracene (S3)) are within the visible light region. These results of the dyes confirmation that these dyes are possible to be a perfect photosensitizer in solar cells.

Refluxing [Rh(2-phpy)2(Cl)]2 separately with the equivalent amount of 5-phenylazo-8-hydroxyquinoline (Hq1), 5-(4-fluorophenylazo)-8-hydroxyquinoline (Hq2) and 5-(4-nitrophenylazo)-8-hydroxyquinoline (Hq3) in toluene in aerobic condition afforded mononuclear orange coloured compounds having general formula [Rh(2-phpy)2(q)] in excellent yields. The complexes were substantiated by IR, 1H NMR, ESI-mass, EPR, UV–Vis and emission spectra, cyclic voltammetry, single-crystal X-ray structure determinations and density functional theory (DFT) calculations. Synthesis and comparison of their photophysical and electrochemical properties of a new branch of rhodium(III) complexes of 8-hydroxyarylazo analogues are presented which are never studied before. The ground and excited-state geometries, absorption, and emission properties of the complexes were examined by DFT and TDDFT methods. The excitations and emissions are investigated by the natural transition orbital (NTO) analysis. The emission occurred via 3MLCT or 3ILCT transition by theoretical analysis of triplet state DFT calculations. The cis-trans isomerism studies for the azo complexes have been done by experimental as well as theoretical analysis.

In this work, a series of novel D-π-A structure coumarin-benzoxazole derivatives have been synthesized. The third-order NLO properties of the coumarin derivatives in DMSO are investigated by Z-scan measurement, and the photophysical properties of the compounds are studied through experimental and theoretical calculation methods. The results showed that the introducing specific functional groups at multiple active sites of coumarin reduced the π-π intermolecular stacking, while the formation of push-pull structure decreased E-gap of entire molecule. The excellent third-order NLO responses based on chromophore 4c with maximum nonlinear absorptive coefficients is 50.64 × 10−13 esu and the largest second-order NLO hyperpolarizability is 7.12 × 10−30 esu. Experimental results have also been confirmed through DFT, TDDFT and ZINDO calculations. Our results indicate that the coumarin fluorescent dyes are promising candidate materials for NLO applications.

A tetradentate Schiff base ligand, (4-nitro-N,N′-o-phenylene-bis(5-methoxysalicylideneimine)) (H2L), and its cobalt(II) complex (CoL•DMF) were synthesized. Elemental analysis, and FT-IR and 1H NMR spectra were used to confirm the molecular structure of H2L ligand. In addition, elemental analysis, molar conductance measurement, infrared and electronic absorption spectroscopies as well as single crystal X-ray diffraction were employed to distinguish the molecular structure of the complex that has a slightly distorted square-planar geometry around the cobalt(II) ion. The geometries of H2L and CoL were optimized by means of the DFT/(U)PBE0/Def2-TZVP level of theory. Good agreement of the optimized geometric parameters of the complex with the corresponding experimental ones and successfully reproduction of the FT-IR spectra of the ligand and complex validated the applied method. Based on the optimized structure of CoL, its electronic absorption spectrum was reproduced by using time-dependent density functional theory (TDDFT) at the same level. Its analysis was carried out to assign the observed electronic transitions and determine their characters. The computed nonlinear optical (NLO) parameters (β, γ and values) of H2L and CoL by using TDDFT at the same level combined with the sum-over-states (SOS) method are considerable larger values than reference compound i.e. urea. The ligand and the complex in the absence of nitro and methoxy moieties referred to as H2L′ and CoL′ respectively were optimized to elucidate the effect of these moieties on hyperpolarizabilities values.

The present work focuses on the design and development of new thienopyrazine-derivatives in alternate Donor-Acceptor (D-A) structure for solar cells applications. Eight molecules based on thienopyrazine combined with the electron-rich thiophene or bithiophene units have been investigated using the DFT and TDDFT methods with B3LYP functional implemented with 6-31G(d,p) basis set. The focus was on the effect of substitution and doping on the structural, optoelectronic, photovoltaic and transporting properties. The result shows that the substitution by bithiophene groups decreases energy gap (Eg), produces a high bathochromic shift and increases oscillator strength of the lowest-lying transition compared to the substitution with thiophene groups. The doping of studied molecules makes them more planar and improves their electronic properties. Other characteristics, such as the ionization potential (IP), electronic affinity (EA), reorganization energies (λ+ and λ−), voltage in open circuit (Voc), and charge transfer are discussed. All of the molecules show moderate values of voltage in open circuit and efficient charge transfer. In the light of these results, we suggest promising models of systems for applications in optoelectronic. OPVC solar cell based on the most appropriate designed molecule (low band gap and high VOC) in bulk heterojunction composite with [6,6] -phenyl-C61-butyric acid methyl ester (PCBM) as an acceptor has been modeled. A model energy band diagram is described for OPVC to simulate the energy transfer between active layers. These materials are potentially interesting for the realization of optoelectronic devices and can be qualified as future materials for renewable energy.

Density functional theory (DFT) and time-dependent DFT calculations using the CAM-B3LYP functional were performed to investigate the electronic and optical properties of 2,7-Ph2-naphtho[1,2-d:5,6-d′]bis-(oxaphosphole) (Ph2-NBOP). Furthermore, we examined the effect of several structural modifications of Ph2-NBOP on the energy gap between the highest occupied and lowest unoccupied molecular orbital (HOMO and LUMO, respectively). The HOMO-LUMO gap (ΔEH-L) can be tuned by controlling the π-orbital overlap. Substituting As for P hinders the effective π-orbital overlap due to the inherently different size of pz orbitals perpendicular to the molecular plane, and results in a decrease of ΔEH-L (5.58 eV) than that (5.79 eV) of Ph2-NBOP. Moreover, asymmetric addition of substituents to the terminal phenyl ring increases the polarization of P or As, leading to a decrease in ΔEH-L due to the more ionic character of the corresponding bonds. Based on these results, we designed a minimal ΔEH-L model (CN1(NH2)1-NBOAs), P atoms of Ph2-NBOP are replaced to As and both CN and NH2 are attached to the terminal points of the phenyl rings of Ph2-NBOP, whose ΔEH-L (4.88 eV) is almost 1 eV smaller than that (5.79 eV) of Ph2-NBOP.

The density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods have been used to study the electronic structure, absorption and emission spectra, charge injection/transport ability and phosphorescence quantum efficiency of a series of cyclometalated iridium(III) complexes with carbazate ancillary ligands. Complexes 2–5 introduce electron-withdrawing group sulfuryl fluoride (–SO2F) on benzene ring of ppy (2-phenylpyridine) ligands to increase the steric effect. The introduction O, S atoms and C˭C double bond increases the conjugated degree of complexes. Compared with experimental complex 1, the absorption/emission spectra of complexes 2 and 3 are blueshifted. Complexes 2 and 5 have better charge transporting ability. Complexes 3 and 6 may possess higher quantum efficiency and better hole and electron injection ability, and complex 3 could be the potentially efficient blue light materials.

Triphenylamine-based cyclometalated platinum(II) (TCP) emits phosphorescence at room temperature. The phosphorescence was quenched by oxygen molecule, which means that TCP is a good candidate for oxygen molecule recognition and measurement. By the way of quantum chemical calculation, we proposed the quenching mechanism to elucidate the nature of oxygen sensing, which was different from the traditional dynamic collision mechanism. The luminescence mechanism of TCP involves phosphorescent emission, and the TCP-O2 complex fluorescent emission. By utilizing the density functional theory (DFT) method, we calculated the electron configurations and the frontier molecular orbitals of TCP and the TCP-O2 complex. Furthermore, applying the time-dependent density functional theory (TDDFT) method, we calculated the geometric optimization and the excitation energies of TCP and the TCP-O2 complex in the excited state. The results illustrate that the luminescence of TCP stems from localized excitation, while that of the TCP-O2 complex stems from delocalized excitation. Moreover, we also calculated the radiative and non-radiative rate constants of TCP and the TCP-O2 complex and clarified the photophysical processes of them. For TCP, first the electron arrived at the T1 state via intersystem crossing from the initial S1 state and finally back to the S0 state via emitting phosphorescence. For the TCP-O2 complex, with no spin flip, the electron jumped directly from the T1 to T0 state via internal conversion.

Using time-dependent density-functional theory, we investigate the electronic stopping power of self-irradiated silicon through non-adiabatic dynamics simulations. For specific velocities above 0.5 atom units, electronic stopping shows a generally assumed metallic behavior that is velocity-scaling. While in the lower velocity regime, the slope of electronic stopping power versus velocity changes and the overall magnitude are significantly greater than expectations, leading to the complete vanishing of hard threshold. An analysis of the electron localization function allows us to arrive at the following conclusion: the relative long duration of encounter process between the host atoms and the projectiles with low velocities makes possible the formation of chemical bonds. The continuous formation and breaking of chemical bonds provides an additional effective energy loss channel.

A series of compounds (W1-W8) based on triphenylamine with -C=N- or -NH- group, were designed and studied by fluorescence emission spectra and DFT/TDDFT calculations. Probes W1-W4 were selectively leveraged to sensitively detect glutathione by two distinct reaction mechanisms, thereinto, W1-W2 featured a convenient detection for glutathione using hydrolysis and W3-W4 utilized displacement to probe glutathione possessing sensitivity and practicability. Compound W5-W8 here provided an avenue for understanding structure-property relationship. Taken considerations for toxicity and biocompatibility together, W1-W4 showed great advance for endogenously and exogenously imaging GSH in living cells.

For TNP chemosensor 2-(4,5-Bis(4-Chlorophenyl)-1H-Imidazol-2-yl)-4-Chlorolphenol (HPICI), previous thought with no theoretical basis was that excited-state intramolecular proton transfer (ESIPT) process and the ground-state HPICI-TNP complex are mainly responsible for its fluorescence emission and the detection of TNP. However, this interpretation has been proved to be wrong by the present theoretical DFT/TDDFT explorations. Actually, the strong fluorescence of HPICI is mainly induced by the local excitation of the enol form HPICI(E) without ESIPT, and the fluorescence quenching by TNP is due to the photo-induced electron transfer (PET) process together with the cooperative effect of hydrogen-bonding interaction and π-π stacking interaction coexisting in the HPICI-TNP complex. The strengthened excited-state hydrogen bond promotes the PET process, thus facilitates the fluorescence quenching. This mechanism is proposed on the basis of the theoretical analyses on molecule geometry, binding energy, Gibbs free energy, electronic transitions, and frontier molecular orbitals (FMOs).

A practical and an efficient Schiff base fluorescent chemosensor, salicylidene-4-aminoantipyrinyl-4-aminophenol (A2) has been synthesized through the condensation procedure of 1-phenyl-2,3-dimethyl-4-(N-2-hydroxybenzylidene)-3-pyrazoline-5-one and 4-aminophenol. Compound A2 has displayed a considerable fluorescence enhancement with high selectivity and sensitivity toward Al3+ ion and exhibited an emission band at 484 nm, which contained a low detection limit (LOD) of 1.06 × 10−7 M. In accordance to the experimental study, DFT, TDDFT calculations, and the enhancement of fluorescence intensity might be attributed to the inhibition of Photoinduced Electron Transfer (PET) along with the Excited-State Intramolecular Proton Transfer (ESIPT). As it has been specified by Job's plot and DFT calculations, the binding stoichiometries of A2 with Al3+ are 1:1, while the association constant (Ka) of Al3+ has been calculated and observed to be 2.67 × × 105 M−1. Furthermore, the binding behavior and sensing mechanism of A2 with Al3+ have been confirmed through the experiments of 1H NMR titration.

An anthracene and carbazole based π-conjugated Schiff base (An2Cb) was characterized to emphasize its optical, dielectric and gas sensing properties. UV–Visible absorption spectrum shows three main maxima at 279, 340 and 420 nm with an optical gap of 2.33 eV determined according to Tauc model. Computational analysis by Time Dependent Density Functional Theory (TD-DFT) was used to obtain a UV–Visible absorption spectrum found in good agreement with the experimental chart. The 3D charge distribution was theoretically determined through B3LYP/6–311 + G* basis set. Current-Voltage characteristics of the device are typical to diode behaviour with a trap controlled space charge limited current transfer mechanism. The AC dynamic electrical transport process was studied in function of temperature. It displays a hopping transport process with a thermal activation energy of 0.88 eV. The device is assimilated to an equivalent electrical circuit based on a resistance Rs in series with a resistance Rp which is parallel to a constant phase element CPE. Gas sensing performance was tested. It shows a selective and reversible oxygen sensor at low concentration at room temperature, and an improvement in its sensitivity was observed with increasing temperature until 333 K.

Photodissociation (PD) spectroscopy of protonated guanosine monophosphate (GMPH+) ions was performed using IR-laser ablation of droplet beam and quadruple ion trap techniques. Photofragmentation of GMPH+ gave a protonated guanine ion (GH+) as the main product. A wide-range PD spectrum (3.9–5.4 eV) monitored by the GH+ ion intensity showed four characteristic electronic transitions related to their three different anti glycosyl-bond conformers of GMPH+, which were identified by their π-π* transitions based on time dependent density functional theory calculation. Furthermore, the narrow-bandwidth PD spectrum (4.28–4.33 eV) shows the existence of syn glycosyl-bond conformation with keto form.

Electronic excitations and their dynamics are oftentimes at the foundation of how we use and probe materials. While recent experimental advances allow us to do so with unprecedented accuracy and time resolution, their interpretation relies on solid theoretical understanding. This can be provided by cutting-edge, first-principles theoretical-spectroscopy based on many-body perturbation theory (MBPT) and time-dependent density functional theory (TDDFT). In this work we review some of our recent results as successful examples for how electronic-structure methods lead to interesting insight into electronic excitations and deep understanding of modern materials. In many cases these techniques are accurate and even predictive, yet they rely on approximations to be computationally feasible. We illustrate the need for further theoretical understanding, using dielectric screening as an example in MBPT and faster, more accurate numerical integrators as a challenge for real-time TDDFT. Finally, we describe how incorporating online databases into computational materials research on excited electronic states can side-step the problem of high computational cost to facilitate materials design.