Utjecaj otapala na Hammettove sigma konstante

master's thesis

• Title (english): Solvent effect on Hammett sigma constants
• Author: Matej Kern
• Mentor: Zlatko Mihalić (mentor)
• Committee member: Zlatko Mihalić (predsjednik povjerenstva)
• Committee member: Tomica Hrenar (član povjerenstva)
• Committee member: Nives Galić (član povjerenstva)
• Committee member: Ivan Kodrin (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2019-09-30, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

Ispitan doprinos specifičnih interakcija DMSO-a prilikom računa Hammettovih sigma
konstanti reakcije disocijacije para-supstituiranih benzojevih kiselina. Korištene su
homodezmotske reakcije kako bi se izbjegao značajno zahtjevniji račun solvatacije protona u
DMSO-u. Račun geometrija, slobodne energije solvatacije i termičkih korekcija obavljen je
na PBE0/def2-TZVPD/SMD razini teonije dok su finalne energije računate na B2PLYPD3/
def2QZVPPD razini. Solvatacija je opisana kontinuumom te klaster-kontinuum metodom
s do 3 molekule vode, odnosno jednom molekulom DMSO-a u klasteru. Valjanost metode
potvrđena je usporedbom izračunatih pKa vrijednosti u vodi s literaturnima. Metoda se
pokazala uspješnom u računu pKa vrijednosti u vodi uz upotrebu 2 ili 3 molekule vode u
klasteru. Račun kontinuum solvatacijom u DMSO-u pokazao je izvrsno slaganje s literaturnim
podacima. Klasteri s molekulom DMSO-a dali su lošije rezultate od samo kontinuum
solvatacije uzrok čega bi trebalo istražiti.

Abstract (english)

The disociacion of para-benzoic acids in water and DMSO was investigated to estimate the
contribution of specific solvent interactions in the calculation of Hammett σ constants.
Homodesmic reactions were used to achieve the maximal cancelation of error caused by
deficiencies at this level of theory. Calculation of geometries, standard Gibbs solvation
energies and thermal corections was done at the PBE0/def2-TZVPD/SMD level, while single
point energies were computed at the B2PLYP-D3/def2-QZVPPD level of theory. Solvation
was modeled by continuum and cluster-continuum methods with up to three discrete
molecules of water or one molecule of DMSO pressent in the clusters. Validation of the
method was done by pKa calculation in water which was in good agreement with values taken
from literature for clusters containing two or three molecules of water. Calculations in DMSO
using continuum solvation showed agreement with literature as good as the best water
clusters. DMSO clusters predicted worse results which merits further investigation.

• Keywords: Hammett sigma; DFT; DMSO; klaster-kontinuum; benzojeve kiseline; pKa
• Keywords (english): Hammett sigma; DFT; DMSO; cluster-continuum; benzoic acid; pKa
• Language: croatian
• URN:NBN: urn:nbn:hr:217:599367
• Study programme: Title: Graduate university studies in chemistry; specializations in: Research programme; Course: Research programme; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra kemije (magistar/magistra kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-10-17 14:08:33