engleski

Can MEPs obtained from DFT calculations be used to a priori determine the effectiveness of the employed supramolecular strategies?

Crystal engineering as an interdisciplinary science with the aim of obtaining desired structural topologies and material properties in the solid-state envelops many different fields of research. In the last ten years computational chemistry has been getting more and more applications in crystal engineering and the study of molecular electrostatic potentials is showing great promise as a useful tool to rationalize and even predict observed synthons for both halogen[1] and hydrogen[2] bonds. However, research in the metal-organic setting and all of its potential properties unlocked by employing metal centers still needs to be furthered and we believe that computational methods will prove to be invaluable to extend our understanding of these systems. The question remains, can we use in-silico methods to apriori determine the outcome of employed strategies for supramolecular synthesis in the metal-organic setting? In an attempt to answer this conundrum we have opted to obtain 1-D supramolecular chains in the metal-organic solid state using the R22(8) synthon formed by lactam groups. β-diketonato complexes of CoII, NiII and CuII with pentane-2, 4-dione and hexafluoropentane-2, 4-dione were used as starting building blocks and pyrimidin-4-one and quinazolin-4-one were used to introduce the lactam groups. A total of ten compounds were prepared employing different ligands to ensure that we have a sufficiently large set of crystal structures to adequately test our hypothesis. Molecular electrostatic potentials calculated via DFT methods on generated geometries were used in an attempt to predict the supramolecular outcome of our synthesis. In all but two cases the analysis of the difference between MEP values on β - diketonato and lactam oxygen atoms enabled us to postulate that the formation of supramolecular synthons between lactam groups is favored. The obtained crystal structures were in accordance with our predictions and in seven out of ten crystal structures R22(8) motifs and in one crystal structure a C(4) motif between lactam groups was observed.

supramolecular chemistry, hydrogen bonding, MEP calculation

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