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Tris(pyrazol-1-yl)borate and tris(pyrazol-1-yl)methane: A DFT study of their different binding capability toward Ag(I) and Cu(I) cations
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Inorganica Chimica Acta
Volume 362, Issue 12, 15 September 2009, Pages 4358-4364
Tris(pyrazol-1-yl)borate and tris(pyrazol-1-yl)methane: A DFT study of their different binding capability toward Ag(I) and Cu(I) cations (Article)
Casarin, M.acd , Forrer, D.ad, Garau, F.a, Pandolfo, L.ad, Pettinari, C.b, Vittadini, A.cd
a Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo 1, 35131 Padova, Italy
b Dipartimento di Scienze Chimiche, Camerino, Italy
c Istituto di Scienze Molecolari, CNR, Padova, Italy
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Abstract
Density functional theory has been used to study the electronic structure of [M(tp)] and [M(tpm)]+ conformers (M = Cu, Ag; tp = tris(pyrazol-1-yl)borate anion, tpm = tris(pyrazol-1-yl)methane) and the energetics of their interconversions. Results for the free tp ligand are similar to those of tpm [M. Casarin, D. Forrer, F. Garau, L. Pandolfo, C. Pettinari, A. Vittadini, J. Phys. Chem. A 112 (2008) 6723], indicating an intrinsic instability of the tripodal conformation (κ3-like). This points out that, though frequently observed, the κ3-coordinative mode is unlikely to be directly achieved through the interaction of M(I) with the κ3-like tp/tpm conformer. Analogously to the [M(tpm)]+ molecular ions, the energy barrier for the κ2-[M(tp)] → κ3-[M(tp)] conversion is computed to be negligible. Though κn-[M(tp)] and κn-[M(tpm)]+ (n = 1, 2, 3) have similar metal-ligand covalent interactions, the negative charge associated to the tp ligand makes the M-tp bonding stronger
Tris(pyrazol-1-yl)borate and Tris(pyrazol-1-yl)methane: A DFT Study of Their Different Binding Capability Toward Ag(I) and Cu(I) Cations
No full textDensity functional theory has been used to study the electronic structure of [M(tp)] and [M(tpm)]+ conformers (M = Cu, Ag; tp = tris(pyrazol-1-yl)borate anion, tpm = tris(pyrazol-1-yl)methane) and the energetics of their interconversions. Results for the free tp ligand are similar to those of tpm [M. Casarin, D. Forrer, F. Garau, L. Pandolfo, C. Pettinari, A. Vittadini, J. Phys. Chem. A 112 (2008) 6723], indicating an intrinsic instability of the tripodal conformation (k3-like). This points out that, though frequently observed, the k3-coordinative mode is unlikely to be directly achieved through the interaction of M(I) with the k3-like tp/tpm conformer. Analogously to the [M(tpm)]+ molecular ions, the energy barrier for the k2-[M(tp)] → k3-[M(tp)] conversion is computed to be negligible. Though kn-[M(tp)] and kn-[M(tpm)]+ (n = 1, 2, 3) have similar metal–ligand covalent interactions, the negative charge associated to the tp ligand makes the M-tp bonding stronger
Role and Effective Treatment of Dispersive Forces inMaterials: Polyethylene and Graphite Crystals as Test Cases
No full textA semiempirical addition of dispersive forces to conventional density functionals (DFT-D) has been implemented into a pseudopotential plane-wave code. Test calculations on the benzene dimer reproduced the results obtained by using localized basis set, provided that the latter are corrected for the basis set superposition error. By applying the DFT-D/plane-wave approach a substantial agreement with experiments is found for the structure and energetics of polyethylene and graphite. two typical solids that are badly described by standard local and semilocal density functionals
Vapochromic properties versus metal ion coordination of β-bispyrazolato–copper(ii) coordination polymers: a first-principles investigation
No full textA series of monoadducts of the β-bispyrazolato–copperIJII) one-dimensional coordination polymer is investigated with plane-wave density functional theory–dispersive interactions (DFT-D) calculations. It was found that weak Lewis bases, such as H2O and CH3OH, prefer a symmetric bridging coordination to the Cu(II) ions, which in turn assume a highly distorted 4 + 2 octahedral configuration. Stronger Lewis bases,
namely, NH3 and pyridine, prefer instead to bind to a single Cu(II) ion, which adopts a 5-fold coordination in a square-pyramidal environment. A semi-bridging coordination, corresponding to a 5 + 1 distorted octahedral Cu(II) environment, is finally predicted for molecules of intermediate Lewis basicity, such as CH3CN. The soundness of these results is corroborated by a good correlation found between the theoretical coordination number of the Cu(II) ions, the computed spin-down fundamental band gap, and the experimentally observed vapochromic effects
Role and Eective Treatment of Dispersive Forces in Materials
No full textDFT and DFT-D calculations have been carried out on several chemical systems, ranging from molecules to crystalline polymers, bulk graphite, self-assembled phases of large molecules on metal surfaces and small molecules absorbed in porous organic-inorganic materials.
Joining insights from calculations with experimental outcomes, the structural and electronic behavior of complex chemical systems have been described and explained, allowing a deeper understanding of the studied phenomena. Thanks to the implementation of a correction scheme to DFT, allowing the effective treatment of dispersion forces in materials, accurate calculations on previously unaffordable problems have been performed at a reasonable computational effort. This allowed, e.g., to understand the coverage-dependent phase transition of iron phthalocyanine on Ag(110) and the successful modeling of water absorption in a bispyrazolato copper(II) polymer.In questa tesi è presentata un'indagine computazionale basata sulla Teoria del Funzionale Densità (DFT), eseguita su un ampio range di sistemi che spazia da molecole a polimeri cristallini, grafite, fasi auto-organizzate di molecole organiche su supporti metallici e piccole molecole assorbite in materiali porosi a base organica-inorganica.
Combinando le informazioni ottenute per mezzo di metodi computazionali con i risultati sperimentali, prevalentemente di microscopia a scansione ad effetto tunnel, è stato possibile descrivere il comportamento elettronico e strutturale di tali sistemi e raggiungere una compresione dettagliata del loro comportamento chimico-fisico. Grazie all'implementazione di uno schema correttivo per l'inclusione delle forze di dispersione nella DFT, sono stati effettuati calcoli accurati su sistemi altrimenti inaccessibili, pur contendo lo sforzo computazionale. Questo ha permesso, ad esempio, di capire il ruolo giocato dal ricoprimento della superficie nella transizione di fase osservata per le ftalocianine di ferro depositate su Ag(110) e di modellare con successo l'assorbimento di H20 in un polimero di Cu(II) bispirazolato
Influence of the pore size of reversed phase materials on peptide purification processes.
No full text"Effect of high pH column regeneration on the separation performances in reversed phase chromatography of peptides"
No full text"Peptide Purification: Optimization of a Reversed-Phase Chromatographic Purification Step and Effect of Cleaning in Place"
No full text
Role and Effective Treatment of Dispersive Forces in Materials: Polyethylene and Graphite Crystals as Test Cases.
No full textA semiempirical addition of dispersive forces to conventional density functionals (DFT-D) has been implemented into a pseudopotential plane-wave code. Test calculations on the benzene dimer reproduced the results obtained by using localized basis set, provided that the latter are corrected for the basis set superposition error. By applying the DFT-D/plane-wave approach a substantial agreement with experiments is found for the structure and energetics of polyethylene and graphite. two typical solids that are badly described by standard local and semilocal density functionals
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