Absorption spectra of PS in the ultraviolet and infrared region.

The line list is essential for accurately modeling various astrophysical phenomena, such as stellar photospheres and atmospheres of extrasolar planets. This paper introduces a new line database for the PS molecule spanning from the ultraviolet to the infrared regions, covering wavenumbers up to 45000 cm and containing over ten million transitions between 150,458 states with total angular momentum J < 160. Accurate line intensities for rotational, vibrational and electronic transitions are generated by using the general purpose variational code DUO.

Structure of the Se Isomers─An Ab Initio Study.

This study investigates the equilibrium geometries of four different Se isomers using the coupled cluster single and double perturbative (CCSD(T)) method, extrapolating to the complete basis sets. The ground-state geometry of the Se isomer with the C structure (2.8715 Å, 2.

calculations of the spectra and lifetimes of the lead dimer.

Owing to the key role of the lead dimer (Pb) as a heavy element benchmark for the Group IV-A dimers the assignment of its spectroscopic properties and chemical bonding is an important undertaking. To meet this demand, the present work provides comprehensive and detailed information on electronic structure and properties comprising a wide set of Pb states. Calculations are performed by a high-level approach.

MRCI Study of the Electronic Structure and Transition Properties of a Tin Dimer.

The ground and excited states of Sn are calculated using the multireference configuration interaction method combined with Davidson correction (MRCI+Q). The influence of the spin-orbit coupling (SOC) effect on the electronic structure is also considered by the state interaction method of Breit-Pauli Hamiltonian. In the calculations, the potential energy curves and spectroscopic constants of 23 Λ-S states and 31 Ω states of Sn are obtained.

Theoretical study of the spectroscopy and radiative transition probabilities of Si from visible to infrared.

High level calculations on the electronic states of a silicon dimer (Si) have been carried out by employing a multi-reference configuration interaction plus Davidson correction (MRCI + Q) approach with the aug-cc-pVQZ basis set. The scalar relativistic correction is taken into consideration by the second-order Douglas-Kroll-Hess approximation. In the present work, the transition properties (oscillator strength, Einstein spontaneous emission coefficient and radiative lifetime) of the singlet-singlet, triplet-triplet, and quintet-quintet transitions of Si are discussed.

Multidimensional Structure Conformation of Persulfurated Benzene for Highly Efficient Phosphorescence.

It is a challenge to acquire, realize, and comprehend highly emissive phosphorescent molecules. Herein, we report that, using persulfurated benzene compounds as models, phosphorescence can be strongly enhanced through the modification of molecular conformation and crystal growth conditions. By varying the peripheral groups in these compounds, we were able to control their molecular conformation and crystal growth mode, leading to one- (1D), two- (2D), and three-dimensional (3D) crystal morphologies.

A Fully Conjugated Planar Heterocyclic [9]Circulene.

Fully aromatic []circulenes have only been known to encompass up to eight aromatic rings ( = 8), with no reports of endeavors in the synthesis of higher-order analogues ( > 8). Herein we present the first [9]circulene, formally a diazatrioxa[9]circulene, along with a tetrahydro-diazatetraoxa[10]circulene. The key transformation, for construction of the macrocyclic framework, is a simple high-yielding dimerizing condensation between 3,6-dihydroxycarbazole and glyoxal.

Molecular Phosphorescence in Polymer Matrix with Reversible Sensitivity.

Ultralong organic phosphorescence strongly depends on the formation of aggregation, while it is difficult to obtain in dilute environments on account of excessive internal and external molecular motions. Herein, ultralong single-molecule phosphorescence (USMP) at room temperature was achieved in the monomer state by coassembling biphenyl and naphthalene derivatives at low density with poly(vinyl alcohol) (PVA), where PVA provides a confined environment to stabilize the triplet state. Various factors that affect the USMP were studied, including aggregation, conformation, temperature, and moisture.

Benzoselenophenylpyridine platinum complexes: green versus red phosphorescence towards hybrid OLEDs.

The first examples of phosphorescent platinum complexes bearing 2- and 3-(2-pyridyl)benzo[b]selenophenes (PyBSe) were synthesized and fully characterized. Almost identical ionization potential values (5.6 and 5.

Growth of Silver Nanoparticles Using Polythiocyanatohydroquinone in Aqueous Solution.

Motivated by evidence that silver nanoparticles have found numerous technological applications we have explored in this work utilization of polythiocyanatohydroquinone as a new efficient reducing and stabilizing agent for the preparation of such nanoparticles. The formation of silver nanoparticles has been confirmed by the UV-Vis spectroscopy, X-ray powder diffraction and by transmission electron microscopy. The potentiometric and spectroscopy kinetic measurements during the nanoparticles growth are also presented.

Singlet Oxygen Photophysics in Liquid Solvents: Converging on a Unified Picture.

Singlet oxygen, O(aΔ), the lowest excited electronic state of molecular oxygen, is an omnipresent part of life on earth. It is readily formed through a variety of chemical and photochemical processes, and its unique reactions are important not just as a tool in chemical syntheses but also in processes that range from polymer degradation to signaling in biological cells. For these reasons, O(aΔ) has been the subject of intense activity in a broad distribution of scientific fields for the past ∼50 years.

Super high-energy density single-bonded trigonal nitrogen allotrope-a chemical twin of the cubic gauche form of nitrogen.

A new ambient-pressure metastable single-bonded 3D nitrogen allotrope (TrigN) of trigonal symmetry (space group R3[combining macron]) was calculated using density functional theory (DFT). A comprehensive characterization of this material, comprising thermodynamic, elastic, and spectral (vibrational, UV-vis absorption, and nuclear magnetic resonance) properties, was performed. Using high-throughput band structure calculation, the TrigN phase was characterized as an insulator with an indirect band gap of 2.

Solvatochromic effect in absorption and emission spectra of star-shaped bipolar derivatives of 1,3,5-triazine and carbazole. A time-dependent density functional study.

A series of three star-shaped compounds containing both donor (carbazole) and acceptor (2,4,6-triphenyl-1,3,5-triazine) moieties linked through various linking bridges was studied theoretically at the linear response TD-DFT level of theory to describe their absorption and fluorescence spectra. The concept of a localized charge-transfer excited state has been applied successfully to explain the observed strong solvatochromic effect in the emission spectra of the studied molecules, which can be utilized for the fabrication of color tunable solution-processable OLEDs. The concept is in particularly applicable to donor-acceptor species with a C symmetry point group where the static dipole moment changes dramatically upon electronic excitation.

Benzoannelated aza-, oxa- and azaoxa[8]circulenes as promising blue organic emitters.

In the present work, we studied the synergetic effect of benzoannelation and NH/O-substitution for enhancing the absorption intensity in a series of novel designed benzoannelated aza- and oxa[8]circulenes. Semi-empirical estimations of the fluorescence rate constants allowed us to determine the most promising fluorophores among all the possible benzoannelated aza-, oxa- and mixed azaoza[8]circulenes. Among them, para-dibenzoannelated [8]circulenes demonstrated the most intense light absorption and emission due to the prevailing role of the linear acene chromophore.

Aromaticity of the doubly charged [8]circulenes.

Magnetically induced current densities and current pathways have been calculated for a series of fully annelated dicationic and dianionic tetraphenylenes, which are also named [8]circulenes. The gauge including magnetically induced current (GIMIC) method has been employed for calculating the current density susceptibilities. The aromatic character and current pathways are deduced from the calculated current density susceptibilities showing that the neutral [8]circulenes have two concentric pathways with aromatic and antiaromatic character, respectively.

Structure and spectroscopic characterization of tetrathia- and tetraselena[8]circulenes as a new class of polyaromatic heterocycles.

The FTIR, Raman and UV-vis spectra of the recently synthesized tetrathia[8]circulene and tetraselena[8]circulene compounds have been measured and interpreted in details by the density functional theory (DFT) calculations taking into account the molecular symmetry constrains. The structural and electronic features of the studied compounds have also been discussed in connection with the observed spectroscopic characteristics. Particularly, we have found that despite a slightly non-planar conformation the neutral tetrathia[8]circulene and tetraselena[8]circulene molecules demonstrate bifacial aromatic/antiaromatic nature.

Aromaticity of the completely annelated tetraphenylenes: NICS and GIMIC characterization.

A series of heterocyclic and hydrocarbon [8]circulenes (also named completely annelated tetraphenylenes) were studied by the NICS and GIMIC methods in order to describe their aromatic properties from the magnetic criterion point of view. According to calculations all the hetero[8]circulene molecules demonstrate the bifacial aromatic/antiaromatic nature. The inner octatetraene core of the studied [8]circulenes is characterized by the presence of paratropic ("antiaromatic") ring currents, whereas the outer macrocycle constructed from the five- and six-membered rings possesses the magnetically-induced diatropic ("aromatic") ring current.

Computational and experimental investigation of the optical properties of the chromene dyes.

Absorption and fluorescence spectra of the chromene 3 and chromene 13 dyes are studied experimentally and by density functional theory (DFT) including vibronic structure analysis. Vertical electronic absorption spectra are also calculated with the ab initio multiconfiguration method XMC-QDTP2. The vibronic progression for the S0 → S1 electronic transition is calculated within the Franck-Condon approximation including Dushinsky effect and promoting modes are analyzed.

Tetrathio and tetraseleno[8]circulenes: synthesis, structures, and properties.

Novel sulfur and selenium-bridged [8]circulenes were prepared from octabromotetraphenylene. Structures of these compounds were unambiguously confirmed by X-ray crystallographic analyses. Photophysical and electrochemical investigations of these [8]circulenes suggest their potential applications as electronic materials.

Theoretical study of relationships between structural, optical, energetic, and magnetic properties and reactivity parameters of benzidine and its oxidized forms.

Structural, topological, optical, energetic, and magnetic properties and reactivity parameters of benzidine, its radical cation, and its dication as well as molecular complexes of the benzidine dication with the F(-), Cl(-), Br(-), I(-), NO3(-), HSO4(-), and H2PO4(-) anions were calculated at the B3LYP/6-311++G(2d,2p) level of theory in the CH2Cl2 medium. The CAM-B3LYP functional (as the most reliable one) and the 6-311++G(3df,3pd) basis set were used for the UV-vis absorption spectra prediction. The obtained spectral results are in a good agreement with available experimental data.

State-dependent global and local electrophilicity of the aryl cations.

Two alternative approaches—vertical and adiabatic—are used to estimate global and local electrophilicity (ω and ωk+) indexes for a series of aryl cations in both the ground and first excited electronic states using the well-known Parr scheme. The energy parameters used in these methods are obtained by the B3LYP/6-311++G(2d,2p) calculations of the aryl cations and of their oxidized and reduced forms in acetonitrile medium. The ground state ω values are lower than those for the excited state, which is in accord with the maximum hardness principle.

Design of nanoscaled materials based on tetraoxa[8]circulene.

Nanotubes and two-dimensional sheet-like compounds containing tetraoxa[8]circulene core units are theoretically predicted. The large cavities with a diameter of 6 Å in the 2D sheets could be useful for hydrogen storage. The designed compounds are predicted to adsorb strongly in the visible region and to be a promising material for nanophotonics because of their electron-donor properties (p-type semiconductors).

Single crystal architecture and absorption spectra of octathio[8]circulene and sym-tetraselenatetrathio[8]circulene: QTAIM and TD-DFT approach.

The single crystal architecture of the high-symmetry octathio[8]circulene and sym-tetraselenatetrathio[8]circulene is studied at the density functional theory (DFT) level with the quantum theory of atoms in molecules (QTAIMs) approach to the electron density distribution analysis. The presence of stabilizing intermolecular C---C, C---S and C---Se contacts in the longitudinal and transversal projections of the single crystals is postulated on the grounds of the previous high-resolution X-ray data for octathio[8]circulene; it is supported by the present QTAIM calculations and also predicted in some new details for both circulenes. We suggest that the appearance of the observed red color for the monocrystalline octathio[8]circulene is caused by strong intermolecular interactions between the molecules in the single crystal.

Spectroscopy study of silver nanoparticles fabrication using synthetic humic substances and their antimicrobial activity.

In this present study, silver nanoparticles were synthesized using synthetic humic substances (HSs) as reducing and stabilizing agents. Preference of synthetic HSs over natural humic matter is determined by a standardization problem resolution of the product due to the strict control of conditions of the synthetic HSs formation. It allows to receive the silver nanoparticles with the standardized biologically-active protective shell that is very important for their use, mainly in medicine.

Azatrioxa[8]circulenes: planar anti-aromatic cyclooctatetraenes.

We describe herein the first synthesis of a new class of anti-aromatic planar cyclooctatetraenes: the azatrioxa[8]circulenes. This was achieved by treating a suitably functionalised 3,6-dihydroxycarbazole with 1,4-benzoquinones or a 1,4-naphthoquinone. We fully characterised the azatrioxa[8]circulenes by using optical, electrochemical and computational techniques as well as by single-crystal X-ray crystallography.