The study addresses interconnected issues related to two major types of cycloadditions between adjacent thymines in DNA leading cyclobutane dimers (T<>Ts) and (6-4) adducts. Experimental results are obtained for the single strand (dT)(20) by steady-state time-resolved optical spectroscopy, as well HPLC coupled mass spectrometry. Calculations carried out dinucleoside monophosphate water using TD-M052X method including polarizable continuum model; reliability is checked against CASPT2...

Solar-assisted CO2 conversion into fuels and chemical products involves a range of technologies aimed at driving industrial decarbonization methods. In this work, we report on the development series multifunctional metal-organic frameworks (MOFs) based nitro- or amino-functionalized UiO-66(M) (M: Zr Zr/Ti) supported RuOx NPs as photocatalysts, having different energy band level diagrams, for hydrogenation under simulated concentrated sunlight irradiation. RuOx(1 wt %; 2.2 ± 0.9...

Recent fluorescence studies of DNA duplexes with a simple repetitive base sequence have revealed important collective effects which are very sensitive to conformational disorder. In contrast the monomeric chromophores, whose lifetimes shorter than 1 ps, decays span several decades time. The occurrence excitation energy transfer, evidenced by decay anisotropy on femtosecond time scale, is common feature all examined systems. It explained existence Franck−Condon exciton states, in line UV...

The photochemical properties of the DNA duplex (dA)20·(dT)20 are compared with those parent single strands. It is shown that base pairing increases probability absorbing UVA photons, probably due to formation charge-transfer states. excitation induces fluorescence peaking at ∼420 nm and decaying on nanosecond time scale. quantum yield, lifetime, yield for cyclobutane dimer increase upon pairing. Such behavior contrasts UVC-induced processes.

The fluorescence of calf thymus DNA is studied by steady-state and time-resolved spectroscopy combining upconversion time-correlated single photon counting. spectrum very similar to that a stoichiometric mixture monomeric chromophores, arising from bright ππ* states, contrasts with the existing picture exciplex emission in natural DNA. Yet, decays span over five decades time, 98% photons being emitted at times longer than 10 ps. These findings, association recent studies on model duplexes,...

The study concerns the relaxation of electronic excited states DNA nucleoside deoxycytidine (dCyd) and its methylated analogue 5-methyldeoxycytidine (5mdCyd), known to be involved in formation UV-induced lesions genetic code. Due existence four closely lying potentially coupled states, deactivation pathways these systems are particularly complex have not been assessed so far. Here, we provide a complete mechanistic picture state dCyd/5mdCyd three solvents-water, acetonitrile,...

The triplet excited state of flurbiprofen methyl ester (FBPMe) has been used as a chiral reporter for the two binding sites human serum albumin (HSA). occupation level estimated from regression analysis decays at several [FBPMe]/[HSA] ratios. data agree with high affinity (I and II) that are populated to different extent. A remarkable stereodifferentiation found in drug lifetimes within protein microenvironment.

Transfer of the electronic excitation energy in calf thymus DNA is studied by time-resolved fluorescence spectroscopy. The anisotropy, after an initial decay starting on femtosecond time scale, dwindles down to ca. 0.1. in-plane depolarized decays are described a stretched exponential law. Our observations consistent with one-dimensional transfer mediated charge-transfer excited states.

As there is an urgent need to produce solar fuels from CO2, we here report on the development of a series multimetallic UiO-66(Zr/Ce/Ti) solids-supported RuOx nanoparticles as photocatalysts for selective gas phase CO2 methanation by H2 under simulated sunlight irradiation. The trimetallic based-photocatalyst exhibits higher activity (1,900 μmol g−1 CH4 after 22 h) than analogous mono- [UiO-66(Zr) or UiO-66(Ce)] and bimetallic [UiO-66(Zr/Ce) UiO-66(Zr/Ti)] derivatives, well previous reports...

The effect of metal ions on the excited states guanine nanostructures, short d(TG4T)4 quadruplexes and long G4-wires, are studied by fluorescence spectroscopy. steady-state emission spectra show that both systems exhibit a strong cation effect. Fluorescence decays anisotropy decays, recorded from femtosecond to nanosecond time-scale, reveal following picture. In presence K+, arises mainly delocalized ππ* (excitons), whose decay spans several decades times. contrast, in Na+ is dominated...

Dark DNA light: "Dark" excited states of alternating GC double strands emit fluorescence at 4000 cm−1 higher energy (see spectrum) and with four orders magnitude longer lifetime compared to the bright ππ* states. Such high-energy long-lived are expected play a key role in photoreactivity associated appearance carcinogenic mutations.

Long nanowires formed by ca. 800 guanine tetrads (G4-wires) are studied in phosphate buffer containing sodium cations. Their room temperature optical properties compared to those of the monomeric chromophore 2-deoxyguanine monophosphate (dGMP). When going from dGMP G4-wires, both absorption and fluorescence spectra change. Moreover, quantum yield increases a factor 7.3 whereas average lifetime more than 2 orders magnitude, indicating emission associated with weakly allowed transitions. The...

Abstract The triplet excited states of ( S )‐ and R )‐flurbiprofen (FBP) have been used as reporters for the microenvironments experienced within binding sites human bovine serum albumins. Regression analysis decay provides valuable information on degree protection that these are afforded from attack by a second FBP molecule, oxygen, or other reagents. multiexponential fitting decays can be satisfactorily correlated with distribution drug among two its presence noncomplexed form in bulk...

Abstract The electronic excited states populated upon absorption of UV photons by DNA are extensively studied in relation to the UV‐induced damage genetic code. Here, we report a new unexpected relaxation pathway adenine–thymine double‐stranded structures (AT) n . Fluorescence measurements on hairpins (six and ten base pairs) duplexes (20 2000 reveal existence an emission band peaking at approximately 320 nm decaying nanosecond time scale. Time‐dependent (TD)‐DFT calculations, performed for...

Fluorescence and laser-flash photolysis measurements have been performed on two pairs of diastereomeric dyads that contain the nonsteroidal anti-inflammatory drug (S)- or (R)-flurbiprofen (FBP) (S)-tryptophan (Trp), which is a relevant amino acid present in site I human serum albumin. The fluorescence spectra were obtained when subjected to excitation at 266 nm, where approximately 60% light absorbed by FBP 40% Trp; most remarkable feature observed all was dramatic quenching, residual...

Laser flash photolysis (LFP) has been used to determine the degree of binding (S)- or (R)-flurbiprofen methyl ester (FBPMe) human and bovine serum albumins (HSA BSA, respectively). Regression analysis triplet decay drug (λ = 360 nm) in presence proteins led a satisfactory fitting when considering set three lifetimes; corresponding Afree, AI AII preexponential coefficients can be correlated with FBPMe bulk solution within two known sites. The most remarkable differences between HSA BSA were...

We report here on the interaction dynamics between flurbiprofen (FBP) and tryptophan (Trp) covalently linked in model dyads a complex of FBP with human serum albumin (HSA) probed by time-resolved fluorescence spectroscopy from femto- to nano-second timescales. In dyads, rapid (k > 1010 s−1) dynamic quenching 1FBP* is followed slower 109 remaining 1Trp* fluorescence. Both processes display clear stereoselectivity; rates are 2–3 times higher for (R,S)-dyad. addition, red-shifted exciplex...

Excited-state interactions between (S)- or (R)-flurbiprofen ((S)- (R)-FBP) and thymidine (dThd) covalently linked in dyads 1 2 have been investigated. In both dyads, the only emitting species is 1FBP*, but with a lower fluorescence quantum yield (ϕF) shorter lifetime (τF) than when free solution. These results indicate that dynamic quenching occurs either by electron transfer via exciplex formation, FBP as charge-donating species. acetonitrile, mechanisms are favored, while dioxane formation...