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The adjustment of the main helical scaffold in helicenes is a fundamental strategy for modulating their optical features, thereby enhancing their potential for diverse applications. This work explores the influence of helical elongation (n = 5-9) on the structural, photophysical, and chiroptical features of symmetric oxa[n]helicenes. Crystal structure analyses revealed structural variations with helical extension, impacting torsion angles, helical pitch, and packing arrangements. Through theoretical investigations using density functional theory (DFT) calculations, the impact of helical extension on aromaticity, planarity distortion, and heightened chiral stability were discussed. Photophysical features were studied through spectrophotometric analysis, with insights gained through time-dependent DFT (TD-DFT) calculations. Following optical resolution via chiral high-performance liquid chromatography (HPLC), the chiroptical properties of both enantiomers of oxa[7]helicene and oxa[9]helicene were investigated. A slight variation in the main helical scaffold of oxa[n]helicenes from [7] to [9] induced an approximately three-fold increase in dissymmetry factors with the biggest values of|g lum | of oxa[9]helicene (2.2 × 10 -3 ) compared to|g lum |of oxa[7]helicene (0.8 × 10 -3 ), findings discussed and supported by TD-DFT calculations., (© 2024 The Authors. Chirality published by Wiley Periodicals LLC.)

A series of four novel heteroleptic Cu(I) complexes, bearing bis(1 H -indazol-1-yl)methane analogues as N , N ligands and DPEPhos as the P,P ligand, were synthesised in high yields under mild conditions and characterised by spectroscopic and spectrometric techniques. In addition, the position of the carboxymethyl substituent in the complexes and its effect on the electrochemical and photophysical behaviour was evaluated. As expected, the homoleptic copper (I) complexes with the N , N ligands showed air instability. In contrast, the obtained heteroleptic complexes were air- and water-stable in solid and solution. All complexes displayed green-yellow luminescence in CH 2 Cl 2 at room temperature due to ligand-centred (LC) phosphorescence in the case of the Cu(I) complex with an unsubstituted N,N ligand and metal-to-ligand charge transfer (MLCT) phosphorescence for the carboxymethyl-substituted complexes. Interestingly, proper substitution of the bis(1 H -indazol-1-yl)methane ligand enabled the achievement of a remarkable luminescent yield (2.5%) in solution, showcasing the great potential of this novel class of copper(I) complexes for potential applications in luminescent devices and/or photocatalysis.

Aiming to combine the advantages of both prompt fluorescence and thermally activated delayed fluorescence in single emitter, molecular design of emitters with hybridized locally excited and charge transfer states were investigated by computational approaches and optical spectroscopy. Taking into account the results of the theoretical screening, the most promising derivatives of 9,9-dimethyl-9,10-dihydroacridine and 10-phenyl-10H-phenothiazine-5,5-dioxide based with the different linking topology (meta- and para-isomers) were selected for the synthesis and experimental investigations. Both the compounds exhibit ultraviolet LE emission peaking at ca. 360 nm, green ICT peaking at ca. 510 nm, and deep-blue HLCT emission peaking at ca. 430 nm when they are molecularly dispersed in the solid media of the different polarity. The developed emitters allow to obtain deep-blue electroluminescence for the host-containing OLEDs and green electroluminescence of host-free devices with the efficiency of exciton production of 42 and 73%, respectively. Efficient exciton production is due to the spin-flip switching via thermally activated processes which is much more efficient than prompt fluorescence. Showing the impact of the linking topology, the para-isomer demonstrated more efficient triplet harvesting in OLEDs than meta-isomer. A detailed discussion on the structure-property relationships and on some discrepancies between the results of the results of theoretical calculations and spectral analysis allows to obtain important insights on the photophysical properties of these compounds., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Photodynamic therapy (PDT) applications carried out with the assistance of ultrasound have attracted significant attention in recent years. The use of phthalocyanines, which are an important component as photosensitizers in PDT, is becoming more important day by day. In therapeutic applications, phthalocyanines can promote the production of reactive oxygen species. Motivated by this fact, the syntheses of metal-free ( 2 ), gallium ( 3 ), and indium ( 4 ) phthalocyanines have been achieved by substituting 4-(cinnamyloxy)phthalonitrile for the first time to evaluate their therapeutic applications. Additionally, photophysicochemical, sonophotochemical, and in vitro evaluations of phthalocyanines have been reported. To the best of our knowledge, this is the first study of the use of phthalocyanines with different metal ions as potential photosensitizers for sonophotodynamic therapy (SPDT) applications in gastric cancer cell lines. The results show that the quantum yield of the generation of singlet oxygen increased in sonophotochemical studies (Φ Δ = 0.55 ( 2 ), 0.85 ( 3 ), 0.96 ( 4 )), compared to photochemical studies (Φ Δ = 0.22 ( 2 ), 0.61 ( 3 ), 0.78 ( 4 )). The density functional theory (DFT) results are in good agreement with the experimental results and suggest increased reactivity of phthalocyanines 3 and 4 in various redox processes, thus implying their applicability and usefulness as potential therapeutic agents. These phthalocyanines are effective sensitizers for PDT, sonodynamic therapy (SDT), and SPDT against MKN-28 gastric cancer cell line in vitro. All three treatments decreased cell viability and induced apoptosis in the gastric cancer cell line. However, indium phthalocyanine ( 4 )-mediated SPDT was a more effective treatment modality compared to indium phthalocyanine ( 4 )-mediated PDT and SDT. Also, indium phthalocyanine ( 4 ) was found to be a more effective sensitizer to activate apoptosis compared to the other phthalocyanines. To sum up, phthalocyanine-mediated SPDT enhances the cytotoxic effect on gastric cancer cells more than the effect of SDT or PDT alone.

Magnetic field- and polarization-dependent measurements on bright and dark excitons in monolayer WSe 2 combined with time-dependent density functional theory calculations reveal intriguing phenomena. Magnetic fields up to 25 T parallel to the WSe 2 plane lead to a partial brightening of the energetically lower lying exciton, leading to an increase of the dephasing time. Using a broadband femtosecond pulse excitation, the bright and partially allowed excitonic state can be excited simultaneously, resulting in coherent quantum beating between these states. The magnetic fields perpendicular to the WSe 2 plane energetically shift the bright and dark excitons relative to each other, resulting in the hybridization of the states at the K and K' valleys. Our experimental results are well captured by time-dependent density functional theory calculations. These observations show that magnetic fields can be used to control the coherent dephasing and coupling of the optical excitations in atomically thin semiconductors.

In this research, the circulene molecule was selected, and the electron donor and acceptor groups were attached to improve its optical properties. Large negative values of enthalpies, Gibbs free energies, and exothermic energies of formation for these molecules, especially for the CN-CIR-NHLi molecule, show that their formation is highly reasonable. It was illustrated that the E g of the circulene molecule was lowered in the electron donor and acceptor groups' presence, while the CN-CIR-NHLi and CF 3 -CIR-NHLi molecules have the lowest values of E g . It was observed that the optical properties of circulene molecules were improved in electron donor and acceptor groups' presence. Between these groups, the -CN and -CF 3 as electron acceptors and -NHLi substituents, as electron donor groups, yield higher enhancements on the optical properties of circulene, which is in agreement with the results obtained for E g values. Graphical abstract.

The perovskite CH 3 NH 3 PbI 3 excited-state lifetimes exhibit conflicting experimental results under humid environments. Using ab initio nonadiabatic (NA) molecular dynamics, we demonstrate that the interplay between lead vacancy and water can rationalize the puzzle. The lead vacancy reduces NA coupling by localizing holes, slowing electron-hole recombination. By creating a deep electron trap state, the coexistence of a neutral lead vacancy and water molecules enhances NA coupling, accelerating charge recombination by a factor of over 3. By eliminating the mid-gap state by accepting two photoexcited electrons, the negatively charged lead vacancy interacting with water molecules increases the carrier lifetime over 2 times longer than in the pristine system. The simulations rationalize the positive and negative effects of water on the solar cell performance exposure to humidity., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Hypothesis: In photorheological fluids, subtle molecular changes caused by light lead to abrupt macroscopic alterations. Upon UV irradiation of an aqueous cetyltrimethylammonium bromide (CTAB) and trans-ortho-methoxycinnamic acid (trans-OMCA) solution, for instance, the viscosity drops over orders of magnitude. Multiscale modeling allows to elucidate the mechanisms behind these photorheological effects., Experiments: We use time-dependent DFT calculations to study the photoisomerization, and a combination of atomistic molecular dynamics (MD) and DFT to probe the influence of both OMCA isomers on the micellar solutions., Findings: The time-dependent DFT calculations show that the isomerization pathway occurs in the first triplet excited state with a minimum energy conformation closest to the after photoisomerization predominant cis configuration. In the MD simulations, with sub-microsecond timescales much shorter than the experimental morphological transition, already a clear difference is observed in the packing of the two OMCA isomers: contrary to trans-OMCA, cis-OMCA exposes notable part of its hydrophobic aromatic rings at the micelle surface. This can explain why trans-OMCA adopts rod-like micellar packing (high viscosity) while cis-OMCA spherical micellar packing (low viscosity). Moreover, lowering of the OMCA co-solute concentration allowed us to perform full simulation of the breakup process of the rod-like micelles which are stable prior to isomerization., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Cholesterol (Chol) and ergosterol (Erg) are abundant and important sterols in the plasma membrane of mammalian and yeast cells, respectively. The effects of Chol and Erg on membrane properties, as well as their intracellular transport, can be studied with use of fluorescence probes mimicking both sterols as closely as possible. In the search for new and efficient Chol and Erg probes, we use a combination of theoretical methods to explore a series of analogs. The optical properties of the analogs (i.e. excitation energies, emission energies and oscillator strengths) are examined using time-dependent density functional theory (TDDFT) and their ability to mimic the effects of Chol and Erg on membranes is investigated with molecular dynamics (MD) simulations of each analog in a 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) bilayer. From the set of analogs we find two probes (3a and 3b) to display favorable electronic transition properties as well as strong condensing abilities. These findings can lead to the use of new efficient probes and aid in the understanding of the structural features of Chol and Erg that impart to them their unique effects on lipid membranes., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The UV/Vis titration measurements, vibrational and NMR spectroscopy of isomeric dehydrodibenzopyrido[15]annulenes (DBPA) 1 and 2 clearly show that under proper conditions these macrocycles can achieve fast, quantitative and unselective binding of metal ions. The macrocycle 1 is an example of a hindered amine 2,6-bis(R)pyridine and its isomer 2 of a non-hindered amine 3,5-bis(R)pyridine. The protonation stoichiometry for both 1 and 2 was assumed to be DBPA:H(+)=1:1 and the formation constants logK=4.77±0.02 for 1, and logK=6.78±0.08 for 2 were obtained that well agree with those obtained under similar conditions for a macrocycle containing bipyridine units. The protonation of 2 gave the estimated stoichiometry of 2:H(+)=1:1 while the stoichiometric protonation of macrocycle 1 could not be achieved and the lower stability of the ion pair containing 1H(+) is most likely due to the inaccessibility of the nitrogen atom of 1 to the counterions and solvent molecules. The structures and electronic absorption spectra of 1 and 2, as well as the structures and spectra of 1H(+) and 2H(+), i.e. the species formed by protonation of the pyridine nitrogen, were calculated with the time-dependent DFT method with a B3LYP functional and a 6-31+G(d) basis set. The solvent effects were incorporated by means of the polarizable continuum model (PCM). The agreement of the calculated absorption data for the parent and protonated species with the observed spectra is rather satisfactory. Vibrational IR and Raman spectra of 1, 2, 1H(+) and 2H(+) in vacuo were calculated at the B3LYP/cc-pVTZ level of theory. Macrocycles 1 and 2, and their products protonated by trifluoromethanesulfonic acid (1HOTf and 2HOTf) were also characterized by temperature-dependent FTIR technique known as two dimensional IR correlation analysis. Quite large difference in degradation temperature between macrocycle 1 and 2 and their protonated complexes was measured, indicating that inclusion of proton leads to significant thermal stabilization of dehydroannulene ring., (Copyright © 2014 Elsevier B.V. All rights reserved.)