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TheRI-MP2 and RI-CC2 methods have been employed to determine thepotential energy profiles of neutral and protonated α-naphthol,in their individual forms and microhydrated with 1 and 3 water molecules,at different electronic states. According to calculated results, ithas been predicted that dynamics of nonradiative processes in protonatedα-naphthol is essentially different from that of its neutralhomologue. In protonated α-naphthol, the calculations revealthat 1σπ* state, is the most important photophysicalstate, having a bound nature with a broad potential curve along theOH coordinate of isolated system, while it is dissociative in monohydratedhomologue. In neutral system, similar to phenol, the 1πσ*state, plays the fundamental relaxation role along the O–Hstretching coordinate. Moreover, microhydration strongly affects thephotophysical properties of α-naphthol, mostly by alterationof the 1ππ* PE profile, from a bound statein an isolated analogue to a dissociative state in hydrated systems.Furthermore, it has been found that three water molecules are necessaryfor ground state proton transfer between protonated α-naphtholand water; with a small barrier; (ΔE< 0.1eV). [ABSTRACT FROM AUTHOR]

Abstract: The low lying singlet and triplet electronic excited states of neutral and protonated Acenaphthylene (C12H8, ACYN) and Acenaphthene (C12H10, ACN) have been investigated extensively by RI–MP2 and RI–CC2 methods. The first and second electronic excited tates (S1,S2) of protonated ACYN and ACN have ππ∗ nature and lie in the visible or UV region. Similar to naphthalene, anthracene, and other linear PAHs, the protonation of ACYN and ACN leads to a strong red shift of the electronic transition as compared to the neutral molecule. The calculations indicate a charged transfer character of S1–S0 transition in protonated ACYN and ACN as well as protonated naphthalene. [Copyright &y& Elsevier]

In the present study, molecular geometry, electronic structure, first row transition metal-polyoxometalate interactions, transition metal-H 2 O bonding, and simulated infrared (IR) spectrum of H 2 O ligated/unligated transition metal substituted Keggin type polyoxometalates ([PW 11 O 39 (MII/MIIOH 2)]5-, MII ​= ​Cr, Mn, Fe, Co, Ni, Cu and Zn) have been studied through Density Functional Theory (DFT) calculations. From the results, it has been predicted that the interaction of H 2 O ligand with MII leads to a stable [PW 11 O 39 (MII-H 2 O)]5- complex, without spin crossing during water attachment. The calculations have also revealed that interaction of H 2 O ligand with [PW 11 O 39 (MII)]5- could be discussed in two different classes: when MII is Cr, Mn and Fe, the H 2 O molecule interacts directly to MII from O side, while for MII ​= ​Co, Ni, Cu and Zn, the H-bond interaction between H 2 O and O atoms around the M, leads to the stabilization of POM-H 2 O system. Moreover, it has been predicted that the binding properties of H 2 O strikingly depends on axial 3d z 2 orbital of MII. In this regard, it has been exhibited that the affinity of H 2 O for MII in [PW 11 O 39 (MII)]5- with a filled 3d z 2 orbital, is strongly reduced as measured by increasing in calculated MII-ligand distance. Also, strong contributions of MII 3d as well as the 2p orbitals of five oxygen donor atoms in polyoxometalate cluster results in the bonding interaction between MII and lacunary Keggin polyoxometalate. The DFT-derived IR spectra showed displacement and splitting in four previously known vibrational bands of Keggin-type polyoxometalate, α -[PW 12 O 40 ]3-, owing to transition metal substitution and H 2 O ligation. Molecular geometry, electronic structure, first row transition metal polyoxometalate interactions, transition metal-H 2 O bonding nature, and infrared (IR) spectroscopy of H 2 O ligated/unligated transition metal substituted Keggin type polyoxometalates ([PW 11 O 39 (MII/MIIOH 2)]5-; MII ​= ​Cr, Mn, Fe, Co, Ni, Cu and Zn) is studied by DFT calculations. [Display omitted] • DFT calculation on H 2 O ligated/unligated transition metal substituted Keggin type polyoxometalates. • Study on the molecular geometry, electronic structure and simulated infrared (IR) spectrum of [PW 11 O 39 (MII/MIIOH 2)]5-, MII ​= ​Cr, Mn, Fe, Co, Ni, Cu and Zn. • First row transition metal-polyoxometalate interactions and transition metal-H 2 O bonding in TMSPOMs. [ABSTRACT FROM AUTHOR]