Solvotermalna i mehanokemijska sinteza dipeptidnih i imidazolatnih metaloorganskih mreža
| Autor: | Puškarić, Andreas |
|---|---|
| Přispěvatelé: | Bronić, Josip |
| Jazyk: | chorvatština |
| Rok vydání: | 2020 |
| Předmět: |
metaloorganske mreže
powder diffraction mehanokemija solvotermalna sinteza PRIRODNE ZNANOSTI. Kemija NATURAL SCIENCES. Chemistry difrakcija na polikristalnom uzorku solvothermal synthesis udc:54(043.3) mechanochemistry Kemija. Kristalografija. Mineralogija ZIF-8 metal-organic frameworks Chemistry. Crystallography. Mineralogy |
| Popis: | U okviru ovog rada, solvotermalnom metodom sintetizirana su dva nova koordinacijska polimera s dipeptidnim ligandom, glicil-L-fenilalaninom (Gly-L-Phe) te cinkom i kadmijem kao metalnim centrima M(Gly-L-Phe)2 (M=Zn,Cd). Struktura spojeva je riješena difrakcijom na polikristalnom uzorku te je ustanovljeno da se sastoji od dvije međusobno prožete dvodimenzijske mreže. To je prvi takav primjer u klasi spojeva metal-dipeptidnih metaloorganskih mreža. Sintetizirani spojevi su karakterizirani infracrvenom spektroskopijom, termičkom i elementnom analizom. Parametri sinteze su sustavno istraženi i optimizirani. Solvotermalna sinteza isprobana je i s raznim drugim metalima no bez pozitivnih rezultata. Sinteza je provedena i mehanokemijskim putem te su također dobiveni isti spojevi M(Gly-L-Phe)2 (M=Zn,Cd) no u kraćem vremenu. U drugom dijelu rada, u realnom vremenu in situ je praćen tijek sinteze metaloorganske mreže ZIF-8 pomoću difrakcije sinkrotronskog rendgenskog zračenja. Ustanovljeno je da mljevenjem reaktanata (ZnO i 2-metilimidazola) uz dodatak vodene otopine octene kiseline dolazi do brzog nastanka ZIF-8. Dobivena faza zatim amorfizira, a potom rekristalizira u novi, dosad nepoznati polimorf koji daljnjim mljevenje prelazi u treći polimorf. Novootkriveni polimorf se ne pojavljuje svaki put, što govori o stohastičkom ponašanju reakcije. Dodatkom silicija kao unutarnjeg difrakcijskog standarda reakcija je kvantificirana. Two new coordination polymers composed of dipeptide ligand, glycyl-L-phenylalanine (Gly-L-Phe) and zinc or cadmium ions were synthesized, M(Gly-L-Phe)2 (M=Zn, Cd). Their structures were determined from powder diffraction data and it was found that they are composed of two interpenetrated coordination networks. It is the first example of such structures within the metal-dipeptide class of metal-organic frameworks (MOFs). Synthesized compounds were characterized with infrared spectroscopy, thermal and elemental analysis. Parameters of synthesis were systematically investigated and optimized. Solvothermal synthesis was tried with other metals but without positive outcome. Synthesis was also done by mechanochemical method and it gave the same compounds M(Gly-L-Phe)2 (M=Zn, Cd) but in much shorter time. In second part of thesis, mechanochemical synthesis of ZIF-8 (porous MOF) was monitored by in situ real time synchrotron X-ray diffraction. It was found that milling of ZnO and 2-methylimidazole, with addition of solution of acetic acid, produces ZIF-8 in very short time. By further milling, ZIF-8 becomes amorphous and then recrystallizes into new metastable intermediate phase which, on further milling, transforms to third ZIF-8 polymorph. New polymorph doesn't appear in every repeated reaction which is due to stochastic processes of nucleation from amorphous matrix. Added crystalline silicon as internal diffraction standard makes possible to quantify mechanochemical reaction. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|