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Mauro Causà
Deparment of Chemical and Materials Engineering, Universita' di Napoli "Federico II"
Maximum Probability Domains in molecular crystals and surfaces
The Maximum Probability Domain (MPD) analysis due to Andreas Savin is applyed to molecular crystals and their surfaces. The correlation effects are included using Quantum Monte Carlo techniques. The MPD correlated method will be applied to rare gas solids, organic materials applied in photo-electronics, and to crystal phases relevant in heterogeneous atmospheric chemistry.
Piotr Kasprzycki
Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Hoza 69, 00-681 Warsaw, Poland
The correlation between the proton transfer time and electron density in the inner cavity of porphycenes
Numerical solutions of the Schrödinger equation can nowadays be obtained for reasonably large organic and organometallic molecules with useful accuracy using approximate ab initio or DFT methods. These approximate solutions are also available for porphycene which is an important chromophore [1]. Porphycene and its derivatives show useful properties for material sciences and are also considered excellent photosensitive media for applications in photodynamical therapy of cancer [2]. Several papers have discussed the energy structure and dynamic aspects of hydrogen transfer in this systems [4, 5]. We report on the results of NCI analysis - theoretical tool based on Bader approach [6] - performed for symmetrically and asymmetrically substituted porphycene derivatives. We have carried out DFT calculations at the level B3LYP/6-311(d,p) of theory. These calculations were followed by NCI analysis. Calculations showed a correlation between the value of electron density gradient localized between nitrogen and hydrogen atoms in the inner cavity of a molecule and the time of the proton transfer in the examined systems. Proton transfer times were obtained in a femtosecond transient absorption anisotropy experiment, which is a polarisation-sensitive variant of an ultrafast pump-probe technique. Double hydrogen transfer leads to the change of transition dipole moment directions - transition moment of chemically identical tautomerization product forms an angle of α = (72±2)◦ with that of initially excited form. This change is manifested as variation in transmitted light intensity measured in two orthogonal polarizations. Under appropriate conditions, rise/decay times of anisotropy reflect the kinetics of double hydrogen transfer. We show that quantum theory of atoms in molecules (QTAIM) based on Bader approach is useful not only for detection of covalent bond but also for hydrogen bonds and weak van der Waals interaction. NCI analysis provides the possibility to compare strength of hydrogen bonds in porphycene derivatives, which allows one to predict the proton transfer time for new molecules. Additionally, these approach have helped us to design structure of a derivative with the proton transfer time of the order of tens of picoseconds. Furthermore, substitution in 2,7 and in 10,19 position of porphycene can induce differentiation of hydrogen bonds. The effect is especially evident in the case of 10,19-di-methylporphycene (2MPc) and 2,7-di-t-buthylporphycene (DTBP). This behavior may be the result of asymmetric distribution of electron density in the center of the molecule. This fact can be significant for understanding the mechanism of double hydrogen transfer between inner nitrogen atoms.
References
[1] D. Sanchez-Garcia, J. L. Sessler, Chem. Soc. Rev., 37, 215, (2008). [2] J. C. Stockert, M. Canete, A. Juarranz, A. Villanueva, R. W. Horobin, J. I. Borrell, J. Teixido, S. Nonell, Curr. Med. Chem., 14, 997, (2007) . [4] Ł. Walewski, J. Waluk, B. Lesyng, J. Phys. Chem. A., 114, 2313–2318, (2010). [5] M. Gil, J. Waluk J. Am. Chem. Soc. 5, 129, (2007). [6] E. R. Johnson, S. Keinan, , J. Contreras-García, R. Chaudret, J-P Piquemal, D. Beratant, W. Yang, J. Chem. Theo. and Comp., 25, (2011).
Slawomir J. Grabowski
Faculty of Chemistry, University of the Basque Country UPV/EHU, and Donostia International Physics Center (DIPC),P.K. 1072, 20080 Donostia, Spain IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain
Non-covalent interactions: characteristics and mechanisms of formation - the topological approach
Numerous non-covalent interactions are characterized by the electron charge transfer from the Lewis base unit to the Lewis acid [1]. This is connected with the other processes reflected by the change of geometrical, energetic and topological parameters. For example, different characteristics of the hydrogen bond and various criteria of the existence of this interaction were discussed in the literature [2]. One can mention the topological criteria of Koch and Popelier [3,4]. On the other hand, the hydrogen bond mechanism was discussed in terms of NBO method [5]. Very recently it was found that the hydrogen bond, the halogen bond and other non-covalent interactions are steered by the same processes [6]. This is reflected by the same changes of parameters. For example, the A-H...B hydrogen bond formation is connected with the increase of the positive charge of H-atom and the decrease of its volume. The same changes are observed for X-halogen atom in the A-X...B halogen bond. Various similarities and differences between numerous non-covalent interactions may be discussed.
References
[1] Lipkowski, P.; Grabowski, S. J.; Leszczynski, J. J. Phys. Chem. A 2006, 110, 10296–10302. [2] Grabowski, S.J. Chem.Rev. 2011, 11, 2597-2625. [3] Koch, U.; Popelier, P.L.A. J.Phys.Chem. 1995, 99, 9747-9754. [4] Popelier, P. Atoms in Molecules. An Introduction, Prentice Hall, Pearson Education Limited 2000. [5] Alabugin, I.V.; Manoharan, M.; Peabody, S.; Weinhold, F. J.Am.Chem.Soc. 2003, 125, 5973-5987. [6] Grabowski, S.J. Phys.Chem.Chem.Phys. accepted
Vincent Tognetti and Laurent Joubert
Normandy Univ., COBRA UMR 6014 & FR 3038, Mont Saint Aignan, 76821 cedex, France
QTAIM/DFT descriptors for the description of “weak” interactions
We present here part of our recent work, which aims to design new molecular and atomic descriptors by building a bridge between Density Functional Theory (DFT) and Bader’s Atomsin- molecules (AIM) theory,1 two frameworks that share the same primary ingredient: the electron density. A local point of view will first be presented, dealing with the so-called bond critical points (BCPs). New BCP properties will be investigated,2,3,4,5 based on reduced density gradients and on the variations rates of kinetic, exchange and correlation density energies. Interestingly, these quantities reveal particularly suited to the description of weak interactions, like hydrogen or agostic bonds. Then, we will discuss,6 using Pendás’ Interacting Quantum Atoms scheme,7 to what extent the existence or the absence of such BCPs can be rationalized in terms of integrated interatomic energies, enlightening the fundamental role of exchange channels.8 We will consequently present a fast and accurate protocol for the evaluation of the exchange interaction between two atoms,9 making another promising step in the pathway linking DFT and AIM. 1. R. F. W. Bader, Atoms in Molecules: A Quantum Theory, Oxford University Press (1994). 2. V. Tognetti, L. Joubert, P. Cortona and C. Adamo, J. Phys. Chem. A 113 12322-12327 (2009). 3. V. Tognetti, L. Joubert and C. Adamo, J. Chem. Phys. 132 211101 (2010). 4. V. Tognetti and L. Joubert, J. Phys. Chem. A 115 5505-5515 (2011). 5. V. Tognetti, L. Joubert, R. Raucoules, T. De Bruin and C. Adamo, J. Phys. Chem. A 116 5472-5479 (2012). 6. V. Tognetti and L. Joubert, J. Chem. Phys. 138 024102 (2013). 7. M. A Blanco, A. Martín Pendás and E. Francisco, J. Chem. Theory Comput. 1 1096-1109 (2005). 8. A. Martín Pendás, E. Francisco, M. A. Blanco and C. Gatti, Chem. Eur. J. 13 9362-9371 (2007). 9. V. Tognetti and L. Joubert, in preparation.
Agnieszka Roztoczyńska, Justyna Kozłowska, Paweł Lipkowski, Wojciech Bartkowiak
Theoretical Chemistry Group, Institute of Physical and Theoretical Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 53-370, Wrocław, Poland
Influence of spatial confinement on the cooperativity in the hydrogen-bonded clusters
Cooperativity is a well-known phenomenon and a steering factor of many chemical and physical properties of molecular matter [1-5]. In the present contribution the influence of chemical compression on the hydrogen bond cooperativity has been investigated. For that purpose the cooperativity effects in the isolated and confined (HF)n and (HCN)n clusters were considered. Two models of spatial confinement have been applied in our study. The first one is the cylindrical model harmonic potential, which certainly reflects the general aspects of the confinement effect. The second, less simplified model based on the supermolecular approach: molecular cages within which one can distinguish helium and carbon nanotubes. In order to get an insight into the nature of the cooperative effects in confined spaces a detailed analysis of the energetics and the topological features of electron density according to the concept of the “Quantum Theory of Atoms in Molecules” (QTAIM) proposed by Bader [6,7] have been performed. The properties in question have been analyzed using the ONIOM (M06-2X/6-311++G(2df,2pd):M06-2X/6-31G(d)) method. Moreover, in the case of the harmonic potential calculations, the second-order Møller-Plesset perturbation theory (MP2) has been applied as well. As a part of the study, the comparison of the data obtained within different models of orbital compression have been performed in order to establish the correspondence between the chemical environment and its approximate representations.
[1] A. Korpfen, J. Phys. Chem. 100, 13474 (1996).
[2] T. Kar, S. Scheiner, J. Phys. Chem. A 108, 91619168 (2004).
[3] M. Ziółkowski, S. J. Grabowski, J. Leszczyński, J. Phys. Chem. A 110, 65146521 (2006).
[4] H.J. Song, H.M. Xiao, H.S. Dong, J. Chem. Phys. 125, 074308 (2006).
[5] S. J. Grabowski, Theor. Chem. Acc. 132, 1347 (2013).
[6] R. F. W. Bader, Atoms In Molecules, A Quantum Theory; Oxford University Press: Oxford, U.K., 1990.
[7] R. F. W. Bader, Chem. Rev. 91, 893 (1991).
Paweł Lipkowski, Justyna Kozłowska, Agnieszka Roztoczyńska, Wojciech Bartkowiak
Theoretical Chemistry Group, Institute of Physical and Theoretical Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
Behavior of model hydrogen bonded complexes under the influence of external pressure
Despite of the numerous theoretical and experimental investigations concerning the hydrogen bond phenomenon as well as to the confinement effect there is still a small number of reports on the behavior of the H-bonded systems in the presence of external pressure [1-4]. In order to render the influence of pressure one can apply a model confining potentials which allows to describe the pure valence repulsion contribution. In the present study we have investigated the influence of external pressure, represented by the cylindrical harmonic potential V_conf=1/2(x^2+y^2)ω^2, on the selected linear hydrogen bonded complexes. The model dimeric systems: HF…HF, HCN…HCN, HCN…HCCH have been chosen as a case study. All calculations have been performed employing B3LYP, M06-2X and MP2 methods together with the 6-311++G(2df,2pd) basis set. Moreover the varied external pressure has been controlled by the oscillator strength (ω=0.0-0.8). The studied complexes have been oriented along the z-axis of the Cartesian coordinate system and fully optimized in the presence of the two-dimensional harmonic oscillator potential. A detailed analysis of changes in topological parameters of hydrogen bonds resulting from the orbital compression has been performed according to the concept of the “Quantum Theory of Atoms in Molecules” (QTAIM) proposed by Bader [5,6]. Furthermore an energetic analysis has shown a different manner of the interaction energy in the studied H-bonded complexes.
[1] W. Wang, D. Wang, Y. Zhang, B. Ji, A. Tion, J. Chem. Phys. 134 (2011) 054317.
[2] M.C. Gordillo, J. Marti, Chem. Phys. Lett. 329 (2000) 341.
[3] M. Jabłoński, M. Solà, J. Phys. Chem. A 114 (2010) 10253.
[4] G. Miño, R. Contreras, Chem. Phys. Lett. 486 (2010) 119.
[5] R. F. W. Bader, Atoms In Molecules, A Quantum Theory; Oxford University Press: Oxford, U.K., 1990.
[6] R.F. Bader, Chem. Rev. 91 (1991) 893.
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