Krunoslav Užarević

Krunoslav Užarević

dr. sc.

+385 1 457 1217

1295
1432
Scientific associate

Krilo 3/102-105

Ruđer Bošković Institute
Bijenička cesta 54
10000 Zagreb
Croatia

Bibliography

CV_KUzarevic_2014.doc 146.00 kB

Research Areas

Inorganic Chemistry, Organic Chemistry, Applied Chemistry

Specific research interests

supramolecular chemistry

Awards and Achievements

2009 "National award for excellence" obtained from Ministry of Science, Sports and Education.

Classes

More than 3000 working hours teaching laboratory and seminal courses in General and Inorganic Chemistry for students in chemistry, biology, geology and physics.

Mentor to 10 graduate students in their obtaining of Master Degree. Studies with five of those students were published in four scientific articles.

Mentor to one student project: “Concomitant trimorph of cis-dioxo[(N-3-oxypirid-2-yl)-salicydeneiminato-O,N,O'-methanol] molybdenum(VI)”  awarded by “Dean’s Award”.

Featured Publications

D. Gracin, V. Štrukil, T. Friščić, I. Halasz, K. Užarević, Laboratory real-time and in situ monitoring of mechanochemical milling reactions using Raman spectroscopy, Angew. Chem. Int. Ed. accepted for publication, DOI: 10.1002/anie.201402334R1

● K. Užarević, I. Halasz, I. Đilović, N. Bregović, M. Rubčić, D. Matković-Čalogović and V. Tomišić, Dynamic molecular recognition in the solid state for separating mixtures of isomeric dicarboxylic acids, Angewandte Chemie International Edition (2013) 52, 5504-5508. (corresponding author)

● M. Rubčić, K. Užarević, I. Halasz, N. Bregović, M. Mališ, I. Đilović, Z. Kokan, R. S. Stein, R. E. Dinnebier and V. Tomišić, Desmotropy, Polymorphism, and Solid-State Proton Transfer: Four Solid Forms of an Aromatic o-Hydroxy Schiff Base, Chemistry - A European Journal (2012)  18, 5620–5631; (corresponding author)

● K. Užarević, I. Ðilović, N. Bregović, V. Tomišić, D. Matković-Čalogović, and M. Cindrić, Anion-Templated Supramolecular C3-Assembly for Efficient Inclusion of Charge- Dispersed Anions into  Hydrogen-Bonded Networks, Chemistry - A European Journal (2011), 17, 10889-10897. (corresponding author)

● K. Užarević, M. Rubčić, M. Radić, A. Puškarić, and M. Cindrić, Mechanosensitive metal–ligand bonds in the design of new coordination compounds. CrystEngComm (2011), 13, 4314-4323. (corresponding author)

● I. Halasz, M. Rubčić, K. Užarević, I. Ðilović, and E. Meštrović, The cocrystal of 4-oxopimelic acid and 4,4’-bipyridine: polymorphism and solid state transformations, New Journal of Chemistry (2011), 35, 24–27

● K. Užarević, M. Rubčić, I. Ðilović, Z. Kokan, D. Matković-Čalogović, and M. Cindrić, Concomitant Conformational Polymorphism: Mechanochemical Reactivity and Phase Relationships in the (Methanol)cis-dioxo-(N-salicylidene-2-amino-3-hydroxypyridine) molybdenum(VI) Trimorph, Crystal Growth and Design  (2009), 9, 5327–5333. (corresponding author)

● K. Užarević, I. Ðilović, D. Matković-Čalogović, D. Šišak, and M. Cindrić, Anion-Directed Self-Assembly of Flexible Ligands into Anion-Specific and Highly Symmetrical Organic Solids, Angewandte Chemie International Edition (2008) 47, 7022–7025.

Membership in professional associations / societies

Croatian Chemical Society

Croatian Crystallographic Association

Reviewer for CrystEngComm and Journal of Molecular Structure

Miscellaneous

Scientific interests and motivation

My general scientific interests are in the solid-state chemistry of supramolecular host-guest complexes and in the field of coordination compounds. In my research, I combine and compare solution- and solvent-free approaches for synthesis and manipulation of target compounds. These solid-state approaches include mechanochemistry, thermal methods and gas-solid reactions.

Flexible anion receptors

fig-1

Major part of my research in the field deals with flexible anion receptors, i.e. molecules that employ specific binding functionalities to recognise and selectively bind target specie. During the recognition process, such receptors can change their conformation to adapt to the specific requirements of the guest, and they rarely display high peak selectivity in solution. However, in such systems selectivity is often achieved by selective crystallisation. In our studies, we have developed highly adaptable[1,2] and at the same time highly selective receptor for environmentally important nitrate and sulfate anions. By crystallisation of receptor-anion complexes to hydrogen-bonded networks, these anions were separated form solutions containing large excess of competing anions.

Selective grinding

fig-2

In our latest study[3] we proved that flexible polyamine receptor is capable to recognise and selectively bind  isomeric organic guests from their solid mixtures during the milling process. Regardless of whether the recognition takes place in the solid state via milling or by crystallisation from solution, the resulting supramolecular complexes are the same and the selectivity bias of the receptor towards the guest acids is fully retained. Milling improved yields to quantitative and almost eliminated the use of solvent.

Mechanosensitive metal-ligand bonds in the synthesis of new coordination compounds

fig-3

In the design of discrete and extended coordination systems, synthesis from preorganized homoleptic or heteroleptic coordination compounds is often utilised. Although each of the types is valuable under specific synthetic requirements, heteroleptic complexes tend to be more advantageous when only a certain amount and type of ligands need to be replaced (ancillary).[4] Such an approach also allows a high level of control over the resulting structure because substitution takes place only at strictly defined coordination sites. We employed various solvent-free approaches (mechanochemistry, thermal methods) to selectively remove specific ligand from the central metal coordination sphere, resulting in coordinatively unsaturated compound. Coordinatively unsaturated complexes, due to their higher reactivity, can be considered as “activated” species and as such are better precursors since there is no competition (discrimination) between the departing and the incoming ligand.[4] In our studies we compare solution and solvent-free synthetic approaches which prove to be superior under specific conditions and their respective advantages and weaknesses are object of examination.[5] While our recent studies included complexes with one mechanosensitive bond, we are concentrated on the study of precursors with two or more mechanosensitive sites and they potential application in the controllable synthesis of higher-ordered coordination networks.

Solid-State Tautomerism

fig-4

Specific class of ligands used in our laboratory for synthesis of coordination compounds are characterised by strong intramolecular N…H…O hydrogen bond and can occur in the solid state as keto-amino or enol-imino tautomers. Proton transfer in such compounds is usually related with their reactivity, but also with macroscopic properties such as thermochromism and photochromism. Although such compounds and accompanying phenomena have been widely studied, the mechanism of this apparently simple solid-state rearrangement still presents a number of challenges. Main reason for this is that, in contrast to solution, where different tautomers coexist, in the solid state usually only one tautomer appears. Our studies included synthesis of the compounds comprising keto-amino and enol-imino subunits[6] and a unique example of a Schiff base which have crystallised separately as a two polymorphic pairs of keto-amino and enol-imino tautomers, i.e. desmotrops.[7] The relative stabilities and interconversions of the four phases were assessed via various solution and solid-state methods and evaluated against the results of a computational study. Our findings emphasize the importance of intermolecular forces in stabilization of the less stable keto tautomer in the solid state.

References

[1] K. Užarević, I. Ðilović, D. Matković-Čalogović, D. Šišak, and M. Cindrić, Angew. Chem. Int. Ed. (2008) 47, 7022–7025.

[2] K. Užarević, I. Ðilović, N. Bregović, V. Tomišić, D. Matković-Čalogović, and M. Cindrić,  Chem. Eur. J. (2011), 17, 10889-10897. (corresponding author)

[3] K. Užarević, I. Halasz, I. Đilović, N. Bregović, M. Rubčić, D. Matković-Čalogović and V. Tomišić, Angew. Chem. Int. Ed. (2013) prihvaćen za objavljivanje, doi: 10.1002/anie.201301032. (corresponding author)

[4] K. Užarević, M. Rubčić, I. Ðilović, Z. Kokan, D. Matković-Čalogović, and M. Cindrić, Cryst. Growth Des. (2009), 9,5327–5333. (corresponding author).

[5] K. Užarević, M. Rubčić, M. Radić, A. Puškarić, and M. Cindrić, CrystEngComm (2011), 13, 4314-4323. (corresponding author)

[6] K. Užarević, M. Rubčić, V. Stilinović, B. Kaitner and M. Cindrić,  J. Mol. Struct. 984 (2010), 232-239. (corresponding author)

[7] M. Rubčić, K. Užarević, I. Halasz, N. Bregović, M. Mališ, I. Đilović, Z. Kokan, R. S. Stein, R. E. Dinnebier and V. Tomišić, Chem. Eur. J. (2012)  18, 5620–5631. (corresponding author)