Supramolecular interactions between triphenylphosphine oxide and benzamide evaluated by positron annihilation lifetime spectroscopy

In the present work, intermolecular interactions between triphenylphosphine oxide (TPPO) and benzamide (BZM) has been studied in solid state by Positron Annihilation Lifetime Spectroscopy (PALS) and supported by several analytical techniques (in solid state and in solution) and by computational mode...

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Bibliographic Details
Published in:	Journal of molecular structure Vol. 1134; pp. 298 - 306
Main Authors:	Oliveira, F.C., Denadai, A.M.L., Fulgêncio, F., Oliveira, A.M., Andrade, A.C.A., Melo, A.C.A., Yoshida, M.I., Windmöller, D., Magalhães, W.F.
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 15-04-2017
Subjects:	Positronium formation Triphenylphosphine oxide–benzamide complexes Weak intermolecular interactions Triphenylphosphine oxide–benzamide complexes Positronium formation Weak intermolecular interactions
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Summary:	In the present work, intermolecular interactions between triphenylphosphine oxide (TPPO) and benzamide (BZM) has been studied in solid state by Positron Annihilation Lifetime Spectroscopy (PALS) and supported by several analytical techniques (in solid state and in solution) and by computational modeling (in gaseous phase). Isothermal Titration Calorimetry (ITC) in ethyl acetate solvent showed that complexation is a stepwise process, with 2:1 and 1:1 TPPO/BZM stoichiometries, both driven by entropy. HPLC analysis of isolated single crystal confirmed the existence of a 2:1 TPPO/BZM crystalline complex in solid state. The results of thermal analysis (TGA, DTA and DSC) and FTIR spectroscopy showed that the interactions in the complexes are relatively weaker than those found in pure precursors. Finally, PALS showed higher positronium formation probability (I3) at [TPPO0.62·BZM0.38] and [TPPO0.25·BZM0.75] molar fractions, corroborating the existence of two stoichiometries for the TPPO/BZM system and suggesting greater electronic availability of n- and π-electrons in heterosynton complexes, as resulting of interactions, bring forward new evidences of the participation of electronic excited states on the positronium formation mechanism. [Display omitted] •[TPPO1–x·BZMx] was studied by thermodynamic, spectroscopic and structural techniques.•ITC showed that TPPO/BZM complexation in ethyl acetate solvent is driven by entropy.•[TPPO0.62·BZM0.38] complex in solid state is governed by π staking interactions.•PALS was sensitive to two stoichiometries: [TPPO0.62·BZM0.38], [TPPO0.25·BZM0.75].•Weak interactions in TPPO/BZM complexes affect the positronium formation.
ISSN:	0022-2860 1872-8014
DOI:	10.1016/j.molstruc.2016.12.062