Counterions are deemed "spectators" in aqueous solutions of cationic or anionic molecular metal-oxo clusters. While pH and concentration drive metal speciation as a first approximation, the important effect counterions is usually overlooked never considered standard Pourbaix databases. Alkali for polyoxometalate (POM) clusters control solubility with distinct periodic trends, but evidence alkali over ambiguous. Here we show that simple Nb-POM, [Nb10O28]6– ({Nb10}), converts to oligomers...

Group VII Tc and Re have long been studied to develop both radiopharmaceuticals technologies for nuclear materials management. Fundamental research has targeted understanding this periodic table crossroads where polyoxometalates meets metal-metal bonded complexes. Here we isolated green hygroscopic metastable crystals of (ReVI,oct)2(ReVII,tet)2(OH)2(O)12·H2O (ReVI,VII-green,tet=tetrahedral, oct=octahedral), determined by single-crystal x-ray diffraction. In addition color, Re-L1 X-ray...

Many complex organic molecules (hereafter COMs) have been detected in different regions of the interstellar medium (ISM). In each region, energetic processes - UV irradiation, atom bombardments, etc. that could be linked to formation COMs may occur depending on environment. Several mechanisms were proposed but increasing attention is paid radical recombination reactions. Previous studies showed glycolaldehyde (HC(O)CH2OH) and ethylene glycol (HOCH2CH2OH) are formed by between HC˙O ˙CH2OH,...

Group V Nb-polyoxometalate (Nb-POM) chemistry generally lacks the elegant pH-controlled speciation exhibited by group VI (Mo, W) POM chemistry. Here three Nb-POM clusters were isolated and structurally characterized; [Nb14 O40 (O2 )2 H3 ]14- , [((UO2 )(H2 O))3 Nb46 (UO2 O136 H8 (H2 O)4 ]24- [(Nb7 O22 H2 )4 )7 O)6 ]22- that effectively capture aqueous species from pH 7 to 10. These Nb-POMs illustrate a reaction pathway for control over is driven counter-cations (Li+ ) rather than pH. The two...

The long-standing controversy about the presence of two different emissive minima in lowest excited state cationic push-pull dye o-(p-dimethylamino-styryl)-methylpyridinium (DASPMI) was definitively proved through observation dual emission, evidenced by both experimental (femtosecond up-conversion measurements) and theoretical (density functional theory calculations) approaches. From fluorescence data DASPMI water, time resolved area normalized spectra (TRANES) were calculated, showing one...

Abstract Elucidating the speciation (in terms of concentration versus pH) and understanding formation mechanisms polyoxometalates remains a significant challenge, both in experimental computational domains. POMSimulator is new methodology that tackles this problem from purely perspective. The uses results quantum mechanics based methods to automatically set up chemical reaction network, build models. As result, it becomes possible predict phase diagrams, as well derive insights into large...

Carbon monoxide (CO) is the second most abundant molecule in gas-phase of interstellar medium. In dense molecular clouds, it also present solid-phase as a constituent mixed water-dominated ices covering dust grains. Its presence inferred from its infrared (IR) signals. experimental observations solid CO/water samples, IR frequency splits into two components, giving rise to blue- and redshifted band. However, astronomical observations, former has never been observed. Several attempts have...

It is shown that orbitally degenerate states in highly symmetric systems are split by Jahn-Teller forces which of relativistic origin (that is, they arise from the spin-orbit coupling operator). For example tetrahedral systems, Hamiltonians electronic with spin $1/2$ derived. While both electrostatic and contribute to activity vibrational modes $E$ ${T}_{2}$ symmetry ${}^{2}{T}_{2}$ couplings complementary for ${}^{2}E$ states: The mode active through forces, while forces. parameters have...

The simplicity of the fluorescence pattern ABN is in fact outcome an intricate interplay between locally excited and charge transfer states.

The self-assembly mechanisms of polyoxometalates (POMs) are still a matter discussion owing to the difficult task identifying all chemical species and reactions involved. POMSimulator deals with that complexity in an automated manner.

The POM capsule functions as a redox-active inorganic crown ether. Specifically, Cs + ions are captured in the crown-ether-like pores {Mo 3 Fe O 6 }, which exist on surface of capsule, and electrons stored Mo atoms capsule.

In this work, we report a comparative study of computed excitation energies, oscillator strengths, and excited-state energy gradients (S)-nicotine, chosen as test case, using multireference methods, coupled cluster singles doubles, methods based on time-dependent density functional theory. This system was because its apparent simplicity hides complex electronic structure, several different types valence excitations are possible, including n-π*, π-π*, charge-transfer states, in order to...

The formation of hierarchical nanostructures using supramolecular dumbbell-like species made organic–inorganic polyoxometalate-based hybrids is investigated by combination SAXS and computational methods.

Understanding the aqueous speciation of molecular metal-oxo-clusters plays a key role in different fields such as catalysis, electrochemistry, nuclear waste recycling, and biochemistry. To describe accurately, it is essential to elucidate underlying self-assembly processes. Herein, we apply computational method predict formation mechanisms polyoxovanadates, -niobates, -tantalates. While polyoxovanadates have been widely studied, polyoxoniobates -tantalates lack same level understanding....

Phenalenone (PN) is a very efficient singlet oxygen sensitiser in wide range of solvents. This work uses ab initio quantum chemical calculations (CASSCF/CASPT2 protocol) to study the mechanism for populating triplet state PN responsible this reaction, 3(π–π*) state. To describe detail reaction path, and low-lying excited states have been studied, critical points potential energy surfaces corresponding these located vertical adiabatic energies calculated. Our results show that, after initial...

The excited state dynamics of carbonyl carotenoids is very complex because the coupling single- and doubly states possible involvement intramolecular charge-transfer (ICT) states. In this contribution we employ ultrafast infrared spectroscopy theoretical computations to investigate relaxation trans-8'-apo-β-carotenal occurring on picosecond time scale, after excitation in S2 state. a (slightly) polar solvent like chloroform, one-dimensional (T1D-IR) two-dimensional (T2D-IR) transient reveal...

Polyoxometalates (POMs), ranging in size from 1 to 10's of nanometers, resemble building blocks inorganic materials. Elucidating their complex solubility behavior with alkali-counterions can inform natural and synthetic aqueous processes. In the study POMs ([Nb24 O72 H9 ]15- , Nb24 ) we discovered an unusual trend (termed anomalous solubility) alkali-POMs, which is most soluble smallest (Li+ largest (Rb/Cs+ alkalis, least Na/K+ . Via computation, define a descriptor (σ-profile) use...

In this work, the dynamics of electronic energy transfer (EET) in bichromophoric donor-acceptor systems, obtained by functionalizing a calix[4]arene scaffold with two dyes, was experimentally and theoretically characterized. The investigated compounds are highly versatile, due to possibility linking dye molecules cone or partial structure calix[4]arene, which directs active units same opposite side scaffold, respectively. efficiency EET process between donor acceptor discussed through...

Abstract Photoelectrochemical devices require solid anodes and cathodes for the easy assembling of whole cell thus redox catalysts need to be deposited on electrodes. Typical catalyst deposition involves drop casting, spin coating, doctor blading or related techniques generate modified electrodes where active in contact with electrolyte is only a very small fraction mass. We have developed methodology at electrode based supramolecular interactions, namely CH‐π π–π between surface. This...

Molecular dynamics simulations in aqueous solution reveal the existence of two distinct patterns aggregation low and high charge density Lindqvist-type polyoxometalates (POMs). Our results indicate presence contact solvent-shared ion pairs specific preferential interactions alkalis with POMs. Highly charged POMs are capable breaking apart Li+ Cs+ solvation shell, thus enhancing formation long-lived alkali–POM pairs, where act as an electrostatic "glue" forming large oligomers. Stronger pair...

Same fluorescence paterns, diferent topographies of excited states.

In this computational study, we describe the decay mechanism of DASPMI, providing robust and documented answers to some crucial questions still open debates on photophysical behavior cationic dye. After initial excitation, system evolves along a torsional motion, characterized by quite flat potential energy surface, which crosses an intramolecular charge transfer (ICT) excited state with higher energy. A nonemissive twisted-ICT (TICT) minimum is populated, enhances radiationless deactivation...

We present a density functional theory study for the photochemical water oxidation reaction promoted by uranyl nitrate upon sunlight radiation. First, we explored most stable complex in absence of light. The dark environmen proceeds through condensation monomers to form dimeric hydroxo-bridged species, which is first step toward hydrogen evolution (HER). found triplet-state-driven mechanism that leads formation peroxide and gas. To describe detail this path, characterized singlet triplet...