On the origins of the absorption spectroscopy of pterin and Re(CO)3(pterin)(H2O) aqueous solutions. A combined theoretical and experimental study

DNA structural changes (photo)induced by tricarbonyl (pterin)rhenium(I) complex

We report on interactions of different types of DNA molecules including double-stranded and plasmid DNA as well as polynucleotides (poly[dGdC]2 and poly[dAdT]2) with fac-[ReI(CO)3(pterin)(H2O)] (or Reptr) complex. The interaction was characterized spectroscopically and changes in the plasmid structure were verified by both electrophoresis and AFM microscopy. For comparative reasons, two others related tricarbonyl rhenium(I) complexes, fac-[(4,4'-bpy)ReI(CO)3(dppz)]+ (or Redppz) and fac-[(CF3SO3)ReI(CO)3(2,2'-bpy)] (or Rebpy) were also studied to further explore the influence of the different co-ligands on the interaction and DNA (photo)damage. Data reported herein suggests that DNA molecules can be structurally modified either by direct interaction with Re(I) complexes in their ground states inducing DNA relaxation, and/or through photoinduced cross-linking processes. The chemical nature of the co-ligands modulates the extent of the damage observed.

Computational Quantification of the Zwitterionic/Quinoid Ratio of Phenolate Dyes for Their Solvatochromic Prediction

Solvatochromic dyes are utilized in various chemical and biological media as chemical sensors. Unfortunately, there is no simple way to predict the type of solvatochromism based on the structure of the dye alone, which restricts their design and synthesis. The most important family of solvatochromic sensors, pyridinium phenolate dyes, has the strongest solvatochromism. Using a natural population analysis (NPA) of the natural bond orbitals (NBO) of the phenolate group in the frontier molecular orbitals, it is possible to calculate the relative polarity of the ground state and excited state and, thus to develop a model that can predict the three types of solvatochromism observed for this family: negative, positive, and inverted. This methodology has been applied to thirteen representative examples from the literature. Our results demonstrate that the difference in the electron density of the phenolate moiety in the frontier molecular orbitals is a simple and inexpensive theoretical indicator for calculating the relative polarity of the ground and excited states of a representative library of pyridinium phenolate sensors, and thus predicting their solvatochromism. Comparing the results with the bond length alternation (BLA) and bond order alternation (BOA) indices showed that the NPA/NBO method is a better way to predict solvatochromic behavior.

Insights into Molecular Structure of Pterins Suitable for Biomedical Applications

Pterins are an inseparable part of living organisms. Pterins participate in metabolic reactions mostly as tetrahydropterins. Dihydropterins are usually intermediates of these reactions, whereas oxidized pterins can be biomarkers of diseases. In this review, we analyze the available data on the quantum chemistry of unconjugated pterins as well as their photonics. This gives a comprehensive overview about the electronic structure of pterins and offers some benefits for biomedicine applications: (1) one can affect the enzymatic reactions of aromatic amino acid hydroxylases, NO synthases, and alkylglycerol monooxygenase through UV irradiation of H₄pterins since UV provokes electron donor reactions of H₄pterins; (2) the emission properties of H₂pterins and oxidized pterins can be used in fluorescence diagnostics; (3) two-photon absorption (TPA) should be used in such pterin-related infrared therapy because single-photon absorption in the UV range is inefficient and scatters in vivo; (4) one can affect pathogen organisms through TPA excitation of H₄pterin cofactors, such as the molybdenum cofactor, leading to its detachment from proteins and subsequent oxidation; (5) metal nanostructures can be used for the UV-vis, fluorescence, and Raman spectroscopy detection of pterin biomarkers. Therefore, we investigated both the biochemistry and physical chemistry of pterins and suggested some potential prospects for pterin-related biomedicine.