Istraživanje mehanokemijskih polimorfnih transformacija Ramanovom spektroskopijom in situ

master's thesis

• Title (english): Mechanochemical polymorphic transformations studied by in situ Raman spectroscopy
• Author: Leonarda Vugrin
• Mentor: Marica Ivanković (mentor)
• Committee member: Marica Ivanković (predsjednik povjerenstva)
• Committee member: Hrvoje Ivanković (član povjerenstva)
• Committee member: Ivan Halasz (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2021-07-16, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

Ovaj diplomski rad doprinos je istraživanju mehanokemijskih polimorfnih transformacija. Kao modelni sustav odabran je derivat benzojeve kiseline te njegove transformacije u uvjetima suhog i tekućinom-potpomognutog mljevenja. U kemiji čvrstog stanja mnoga su istraživanja vezana uz temeljne karakteristike polimorfije i faznih prijelaza između polimorfa. Polimorfija je iznimno važna prilikom industrijske proizvodnje čvrstih tvari gdje je bitno da je konačna tvar u određenoj polimofnoj formi s ciljnim fizikalnim i kemijskim svojstvima. Glavni je predmet tih istraživanja priprava različitih polimorfa te određivanje njihovih svojstava uključujući i njihove relativne stabilnosti. U ovom radu istraživan je utjecaj tekućih aditiva na selektivnost i učinkovitost mehanokemijske priprave ciljnih polimorfa. Dobiveni polimorfi 4-nitrobenzojeve kiseline okarakterizirani su pomoću difrakcije rendgenskog zračenja na praškastom uzorku. Utjecaj dodatka malih količina različitih otapala na brzinu i nastanak specifičnog polimorfa istražen je Ramanovom spektroskopijom in situ, a kristalne strukture pripravljenih uzoraka identificirane su difrakcijom na prahu. Korištena su otapala različitih polarnosti odnosno različitih proton-donorskih i proton-akceptorskih svojstava. Prilikom mljevenja polaznog derivata benzojeve kiseline uz dodatak teške vode primijećena je izotopna izmjena vodika karboksilne skupine i deuterija stoga je u svrhu potpunije karakterizacije uz polimorfne transformacije paralelno analiziran i deuterijski kinetički-izotopni efekt. U radu se primjenjuje teorija funkcionala gustoće za optimizaciju struktura i izračun energija odgovarajućih polimorfa s ciljem usporedbe njihove stabilnosti i boljeg razumijevanja eksperimentalno dobivenih rezultata. Uočena je zadovoljavajuća korelacija između rezultata dobivenih računskim metodama i eksperimentalnih podataka što pruža smjernice za daljnje eksperimente i olakšava proučavanje faznih prijelaza odabranog sustava.

Abstract (english)

This work represents a contribution to the research of mechanochemical polymorphic transformations. Using benzoic acid derivatives as model systems, dry and liquid-assisted milling were studied. In solid-state chemistry, fundamental characteristics of polymorphism and their phase transitions have been in the focus of research for decades. Polymorphism is of utmost importance in industrial production of solids where it is essential that the final substance is formulated in the adequate crystalline form having desired physical and chemical properties. The main subject of these studies is the synthesis of different polymorphs and their stability. In this work we have studied the influence of liquid additives on selectivity and eficiency in targeted preparation of polymorphs. The prepared polymorphs were characterized by using powder X-ray diffraction and Raman spectroscopy. The influence of solvents of different polarities and different proton-donor and proton-acceptor properties on the rates and selctivities of polymorphic transformations was examined using in situ Raman spectroscopy, while all the crystal structures were characterised using powder X-ray diffraction data. During the grinding of the starting benzoic acid derivative with the addition of heavy water, an isotopic exchange of hydrogen of the carboxyl group and deuterium was observed. In this master thesis, density functional theory is applied to optimize the structures and calculate the energies of the corresponding polymorphs with the aim of comparing their stability and better understanding of the experimentally obtained results. A satisfactory correlation was observed between the results obtained by computational methods and experimental data, which provides guidelines for further experiments and facilitates the study of phase transitions of the selected system.

• Keywords: mehanokemija; polimorfi; benzojeva kiselina; difrakcija; Ramanova spektroskopija
• Keywords (english): mechanochemistry; polymorphism; benzoic acid; X-ray diffraction; Raman spectroscopy
• Language: croatian
• URN:NBN: urn:nbn:hr:149:376474
• Study programme: Title: Applied Chemistry - Graduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Applied organic chemistry; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra primijenjene kemije (magistar/magistra primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-04-11 09:30:40