Intra- and intermolecular force field parameters for the interaction of actinyl ions (AnO2(n+), where, An = U, Np, Pu, Am n 1, 2) with water have been developed using quantum mechanical calculations. Water was modeled extended simple point charge potential (SPC/E). The resulting consists a form in which interactions are pairwise Lennard-Jones functions plus partial terms. Intramolecular bond stretching angle bending treated harmonic functions. new potentials were used to carry out extensive...

The reaction of [Cu(NCMe)4][PF6] with aromatic acetylenes HC2R and triphosphine 1,1,1-tris(diphenylphosphino)methane in the presence NEt3 results formation hexanuclear Cu(I) clusters general formula [Cu6(C2R)4{(PPh2)3CH}2][PF6]2 (R = 4-X-C6H4 (1-5) C5H4N (6); X NMe2 (1), OMe (2), H (3), Ph (4), CF3 (5)). structural motif complexes studied consists a Cu6 metal core supported by two phosphine ligands stabilized σ- π-coordination alkynyl fragments (together coordination pyridine nitrogen atoms...

The molecular orbital (MO) concept is a useful tool, which relates the ground-state energy with energies (and occupations) of individual orbitals. However, analysis excited states from linear response computations performed in terms initial state MOs or some other forms orbitals, e.g., natural transition Because these orbitals lack respective energies, they do not allow developing consistent picture states. Herein, we argue that Dyson's enable description compatible concepts theory. Dyson...

The photochemistry of nucleobases, important for their role as building blocks DNA, is largely affected by the electrostatic environment in which they are soaked. For example, despite numerous studies thymine solution and there still a debate on photochemical deactivation pathways after UV absorption. Many theoretical models oversimplified due to lack computationally accurate efficient electronic structure methodologies that capture excited state electron correlation effects when nucleobases...

For the first time, lonsdaleite-rich impact diamonds from one of largest Popigai crater (Northern Siberia) with a high concentration structural defects are investigated under hydrostatic compression up to 25 GPa. It is found that, depending on nature sample, bulk modulus for lonsdaleite experimentally obtained by X-ray diffraction in diamond-anvil cells systematically lower and equal 93.3-100.5% average values moduli diamond matrix. Density functional theory calculations reveal possible...

Luminescent metal nanoclusters (NCs) stabilized by natural proteins are of special interest in bioimaging applications. However, the detailed structure protein-templated NCs and nature their emissive states remain poorly understood. A fair amount nonluminescent ions clusters complexed to hinders probing emitting using mass spectroscopy, infrared, or other conventional spectroscopy methods. In this respect, only luminescent excitation spectra distinguish NCs. experimental theoretical joint...

Fluorescent beacons based on silver (Ag) clusters for DNA/RNA detection represent a new type of turn-on probe that fluoresces upon hybridization to target nucleobase sequences. Physical–chemical mechanisms their fluorescence activation still remain poorly understood. We studied in detail the dark Ag induced by interactions Ag–DNA complexes with different DNA In all cases, final result depends neither location precursors (dark clusters) nor spectral properties. The reaction is process similar...

We have studied the excited states and structural properties for complexes of cytosine (dC)10 chains with silver ions (Ag+) in a wide range Ag+ to DNA ratio (r) pH conditions using circular dichroism, steady-state absorption, fluorescence spectroscopy along ultrafast upconversion technique. also calculated vertical electronic transition energies determined nature corresponding some models cytosine–Ag+ complexes. show that presence form duplex stabilized by C–Ag+–C bonds. It is shown i-motif...

In this experimental and theoretical joint study, we used single amino acids as model systems for studying protein–cluster interactions. We probed 12 natural with different functional groups potential templates of fluorescent silver (Ag) nanoclusters obtained by sodium borohydride reduction Ag ions. also calculated the Gibbs free energies complexes formed between Ag+ ions, atoms, two-atom clusters acids' various groups. Only cysteine tyrosine could form clusters. This agrees cluster–amino...

The photophysical and isomerization properties of hybrid molecular compounds that consist photochromic nitro-substituted halogenated spiropyran derivatives bonded to the surface [60]fullerene cage through pyrrolidine bridge were investigated using various functionals basis sets TD-DFT semiempirical quantum-chemical approaches. role nπ* states formed by lone pairs substituents in changing electronic structure was evaluated. Sππ(spiropyran) → intermediate Sππ(merocyanine) channel for...

Gd endohedral complexes of C82 fullerenols were synthesized and mass spectrometry analysis their composition was carried out. It established that the synthesis yields a series Gd@C82Ox(OH)y (x = 0, 3; y 8, 16, 24, 36, 44). The atomic electronic structure properties investigated using density functional theory calculations. shown presence gadolinium increases reactivity fullerenols. is proposed high-spin are promising candidates for application in magnetic resonance imaging.

The statistical quantum chemical/molecular dynamical method is developed and employed to reproduce optical spectra. This technique includes quantum-mechanical calculations on energy states photophysical properties of molecular conformers obtained during simulation. Polycyclic organic molecule estradiol surrounded by solvent particles protein structure including tryptophan fragment under thermodynamical conditions are considered. A wide absorption spectrum over several excited electronic...

Photophysical processes proceeding in polyatomic organic molecules (pyran derivatives and cyanines) excited by high-power laser radiation at 532 nm are studied. Some properties of their changes depending on the structure, solvent, excitation conditions determined. The effect limitation exciting is found. maximum (Kmax = 15.0 initial transmission equal to 70%) was observed for cyanine derivative comparable this fullerenes C60, which widely used as limiters.

Abstract Photophysical properties of polyethylene structures embedding aromatic fragments (benzene, anthracene, 4‐dicyanomethylene‐4 H ‐pyran, tryptophan, and estradiol) responsible for existence lowest electronically excited states were studied by new technique involving the elongation method applied to quantum‐chemical calculations. Absorption spectra some photophysical obtained. The comparison between conventional calculations was made, it is shown that a powerful tool determine as well...

We have studied the excited-state dynamics for i-motif form of cytosine chains (dC)10, using ultrafast fluorescence up-conversion technique. also calculated vertical electronic transition energies and determined nature corresponding excited states in a model tetramer structure. Quantum chemical calculations excitation spectrum structure predict significant (0.3 eV) red shift lowest-energy relative to its absorption maximum, which agrees with experimental spectrum. The lowest excitonic state...

The electronic structure, transition probabilities, and corresponding quantum yields of fluorescence in a family dihalogen-tetraphenyl-aza-BODIPY were calculated at the Time-Dependent Density Functional post-Hartree–Fock levels theory. Excellent agreement between theoretical experimental spectral-luminescent data was achieved with HSE06 functional 6-311G* basis set. Because can be quenched through nonradiative intersystem spin crossing transitions from lowest photoactive singlet state to...