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Interesting properties of dual conformations of thermally activated delayed fluorescence molecules show various novel applications in self-doping systems. However, the species and quantities of self-doping systems are not enough to satisfy the requirements and a theoretical investigation to reveal the self-doping mechanism is highly desired. By analysing the potential energy surface, two stable conformations of TP2P-PXZ-qa (QA) and TP2P-PXZ-qe (QE) are determined. The basic geometric and electronic structures are optimised, frontier orbital distributions and energies are obtained, transition properties are analysed and the energy consumption processes of excited states are analysed. Results indicate that two conformations (QA and QE) coexist in the solid phase, the QA conformation acts as host and the QE conformation acts as guest. Efficient intersystem crossing (ISC) and reverse ISC processes are determined for QE conformation. In addition, a substantial overlap exists between the emission spectrum of the QA conformation and the absorption spectrum of the QE conformation, indicating an effective energy transfer process from host to guest. Thus, relationships between molecular structures and photophysical properties are illustrated and a self-doping mechanism is theoretically revealed. Our work rationalises the experimental observations and offers a theoretical perspective for the self-doping mechanism, contributing to the development of efficient non-doped emitters. [ABSTRACT FROM AUTHOR]

A precise analytical potential energy surface (PES) of HCO(X2A′) is fitted from a great quantity of ab initio energy points computed with the multi-reference configuration interaction method and aug-cc-pV(Q/5)Z basis sets. The whole energy points extrapolated to the complete basis set limit are fitted by the many-body expansion formula. The calculated topographic characteristics are analyzed and compared with the existing work to prove the precision of the present HCO(X2A′) PES. By utilizing the time-dependent wave packet and quasi-classical trajectory methods, the reaction probabilities, integral cross sections, and rate constants are computed. The results are compared in detail with the former results carried out on the other PES. Moreover, the provided information on stereodynamics leads to an in-depth understanding of the role of collision energy in product distribution. [ABSTRACT FROM AUTHOR]

The sensing mechanism of 2-hydroxy-1-naphthaldehyde-(4-pyridinecarboxylic)- hydrazone for [Al.sup.3+] is investigated based on the excited-state intramolecular proton transfer (ESIPT) and photo- induced electron transfer (PET) processes. Absorption and fluorescence spectra are calculated, which are consistent with experimental results. By analyzing the major bond parameters, infrared vibrational spectra as well as frontier molecular orbitals, it can be concluded that the hydrogen bond is enhanced in the first singlet excited state ([S.sub.1]), which can also be visualized by the reduced density gradient function. Potential energy curves are also scanned, which can elucidate that the ESIPT process is more likely to occur in the [S.sub.1] state. Changes in molecular configuration and intensity of fluorescence emission confirmed that the ESIPT and PET processes are forbidden in the presence of [Al.sup.3+]. Key words: ESIPT, hydrogen bond, [Al.sup.3+] sensing, reduced density gradient, potential energy curve. Nous examinons le mecanisme de detection de [Al.sup.3+], du compose 2-hydroxy- naphthaldehyde-(4- pyridicarboxyclique)hydrazone, sur la base du transfert intramoleculaire de proton de l'etat excite (TIPEE) et des processus de transfert electronique induit par photon (TEP). Nos calculs des spectres d'absorption et de fluorescence s'averent coherents avec les valeurs experimentales. En analysant les parametres de liaisons majeures, les spectres vibrationnels infrarouges, ainsi que les orbitales moleculaires frontieres, nous pouvons conclure que la liaison hydrogene est renforcee dans le premier etat excite singlet ([S.sub.1]), ce qui peut aussi etre visualise par la fonction du gradient de densite reduite. Nous balayons egalement les courbes d'energie potentielle, ce qui peut eclaircir le fait que le processus TIPEE a plus de probabilite de se produire dans l'etat [S.sub.1]. Les changements dans la configuration moleculaire et l'intensite de remission de fluorescence confirment que les mecanismes TIPEE et TEP sont interdits en presence de [Al.sup.3+]. [Traduit par la Redaction] Mots-cles: TIPE, liaison hydrogene, courbe d'energie potentielle, detection de [Al.sup.3+], gradient de densite reduite., 1. Introduction Intra- and intermolecular hydrogen bonds are crucial in the study of photochemistry, photophysics, and photobiology [1-4]. Hydrogen bond dynamics have been the subject of a lot of studies [...]