A Theoretical Investigation on the Role of Primary, Secondary, and Tertiary Amine Substituents in Excited State Intramolecular Proton Transfer of p-Amino o-Hydroxy Benzaldehyde.

This article reports a comprehensive theoretical analysis of the dual fluorescence property of three derivatives of p-amino o-hydroxy benzaldehyde molecules, namely, para-N,N-dimethylamino orthohydroxy benzaldehyde (tertiary PAOHBA), para-N-methylamino orthohydroxy benzaldehyde (secondary PAOHBA), and para-amino orthohydroxy benzaldehyde (primary PAOHBA) through ab initio calculations and excited state molecular dynamics. The results revealed that excited-state intramolecular proton transfer is responsible for the dual emission properties of such molecules. The conclusions are made based on the computed vibrational frequencies, excited state antiaromaticity, potential energy surfaces, absorption and emission spectra, and finally, from the excited state dynamics.

Analytic potential energy functions for benzene-water interactions based on accurate calculations and the ghost atom formalism.

This article reports the, so far, best interaction potential energy between benzene and water with analytical function. The accurate intermolecular potential energy of the CH-HO system is calculated from electronic structure theory. The calculations are done at the MP2 level of theory, considering the aug-cc-pVTZ basis set, and the results are comparable with CCSD(T) at the complete basis set (CBS) limit.

Local dynamics drive the C-CX3 (X = H and F) bond photodissociation in acetylacetones.

The primary photodissociation events of acetylacetone and its fluorinated analogs reveal that the translational energy distribution profiles of the CH3 and CF3 radicals follow a barrier-impulsive model for the C-C bond cleavage. Analysis based on the one-dimensional potential energy surfaces in the T1 state, as well as dynamics simulations using on-the-fly semi-empirical potentials, suggest that the C-C bond cleavage proximal to the OH group, in general, is accompanied by proton migration. Interestingly, the near identical fragment translational energy distribution profiles of CH3 radical release from acetylacetone and trifluoroacetylacetone, as well as CF3 radical release from trifluoroacetylacetone and hexafluoroacetylacetone, suggest that the dynamics of formation of CH3/CF3 radicals in acetylacetones appears to be independent of the nature of the substituent on the other end of the molecule.

Supramolecular Gelation Based on Native Amino Acid Tyrosine and Its Charge-Transfer Complex Formation.

Self-assembly of amino acids and short-peptide derivatives attracted significant curiosity worldwide due to their unique self-assembly process and wide variety of applications. Amino acid is considered one of the important synthons in supramolecular chemistry. Self-assembly processes and applications of unfunctionalized native amino acids have been less reported in the literature.

Electron donor-acceptor complex enabled photocascade strategy for the synthesis of -dihydrofuro[3,2-]chromen-4-one scaffolds radical conjugate addition of pyridinium ylide.

A visible-light-induced photocascade strategy is disclosed for the synthesis of -dihydrofuro[3,2-]chromen-4-one scaffolds. The photocascade consists of electron donor-acceptor (EDA) complex enabled formation of arylidene coumarinone, followed by 1,4-radical conjugate addition (1,4-RCA) of an generated pyridinium ylide radical (PyYR) towards diastereoselective formation of the -dihydrofuro[3,2-]chromen-4-one scaffold in good to excellent yield. Thorough mechanistic investigations comprising photophysical, spectroscopic, electrochemical and DFT studies provide further insights into the reaction mechanism.

On the intramolecular vibrational energy redistribution dynamics of aromatic complexes: A comparative study on C6H6-C6H5Cl, C6H6-C6H3Cl3, C6H6-C6Cl6 and C6H6-C6H5F, C6H6-C6H3F3, C6H6-C6F6.

Chemical dynamics Simulation studies on benzene dimer (Bz2) and benzene-hexachlorobenzene (Bz-HCB) as performed in the past suggest that the coupling between the monomeric (intramolecular) vibrational modes and modes generated due to the association of two monomers (intermolecular) has to be neither strong nor weak for a fast dissociation of the complex. To find the optimum coupling, four complexes are taken into consideration in this work, namely, benzene-monofluorobenzene, benzene-monochlorobenzene, benzene-trifluorobenzene (Bz-TFB), and benzene-trichlorobenzene. Bz-TFB has the highest rate of dissociation among all seven complexes, including Bz2, Bz-HCB, and Bz-HFB (HFB stands for hexafluorobenzene).

Post-Transition State Direct Dynamics Simulations on the Ozonolysis of Catechol in an N Bath and Comparison with Gas-Phase Results.

Chemical dynamics simulations on the post-transition state dynamics of ozonolysis of catechol are performed in this article using a newly developed QM + MM simulation model. The reaction is performed in a bath of N molecules equilibrated at 300 K. Two bath densities, namely, 20 and 324 kg/m, are considered for the simulation.

Visiblelight-induced ternary electron donor-acceptor complex enabled synthesis of 2-(2-hydrazinyl) thiazole derivatives and the assessment of their antioxidant and antidiabetic therapeutic potential.

A mild and eco-friendly visible-light-induced synthesis of 2-(2-hydrazinyl) thiazole from readily accessible thiosemicarbazide, carbonyl, and phenacyl bromide in the absence of a metal catalyst and/or any extrinsic photosensitizer is reported. This approach only requires a source of visible light and a green solvent at room temperature to produce the medicinally privileged scaffolds of hydrazinyl-thiazole derivatives in good to outstanding yields. Experimental studies support the formation of a visible-light-absorbing, photosensitized colored ternary EDA complex.

Dynamical Behavior of Aromatic Trimer Complexes in Unimolecular Dissociation Reaction at High Temperatures. Case Studies on CH-CF-CH and CH Trimer Complexes.

The intramolecular vibrational energy redistribution (IVR) dynamics during unimolecular dissociation of aromatic trimers at high temperatures is the primary interest of this study. Chemical dynamics simulations are performed for the unimolecular dissociation of benzene-hexafluorobenzene-benzene (Bz-HFB-Bz) and benzene trimer (Bz-trimer) complexes at a temperature range of 1000-2000 K. Partial dissociation of both the complexes is observed, which leads to a dimer and a monomer in the dynamics.

Construction of diabatic Hamiltonian matrix from ab initio calculated molecular symmetry adapted nonadiabatic coupling terms and nuclear dynamics for the excited states of Na3 cluster.

We present the molecular symmetry (MS) adapted treatment of nonadiabatic coupling terms (NACTs) for the excited electronic states (2(2)E' and 1(2)A1') of Na3 cluster, where the adiabatic potential energy surfaces (PESs) and the NACTs are calculated at the MRCI level by using an ab initio quantum chemistry package (MOLPRO). The signs of the NACTs at each point of the configuration space (CS) are determined by employing appropriate irreducible representations (IREPs) arising due to MS group, and such terms are incorporated into the adiabatic to diabatic transformation (ADT) equations to obtain the ADT angles. Since those sign corrected NACTs and the corresponding ADT angles demonstrate the validity of curl condition for the existence of three-state (2(2)E' and 1(2)A1') sub-Hilbert space, it becomes possible to construct the continuous, single-valued, symmetric, and smooth 3 × 3 diabatic Hamiltonian matrix.

Ab initio calculations on the excited states of Na3 cluster to explore beyond Born-Oppenheimer theories: adiabatic to diabatic potential energy surfaces and nuclear dynamics.

We perform ab initio calculation using quantum chemistry package (MOLPRO) on the excited states of Na(3) cluster and present the adiabatic PESs for the electronic states 2(2)E' and 1(2)A(1)', and the non-adiabatic coupling (NAC) terms among those states. Since the ab initio calculated NAC elements for the states 2(2)E' and 1(2)A(1)' demonstrate the numerical validity of so called "Curl Condition," such states closely form a sub-Hilbert space. For this subspace, we employ the NAC terms to solve the "adiabatic-diabatic transformation (ADT)" equations to obtain the functional form of the transformation angles and pave the way to construct the continuous and single valued diabatic potential energy surface matrix by exploiting the existing first principle based theoretical means on beyond Born-Oppenheimer treatment.

Single surface beyond Born-Oppenheimer equation for a three-state model Hamiltonian of Na3 cluster.

When a set of three states is coupled with each other but shows negligibly weak interaction with other states of the Hilbert space, these states form a sub-Hilbert space. In case of such subspace [J. Chem.