Search results for "molekyylit"
showing 10 items of 69 documents
Interplay of spin-dependent delocalization and magnetic anisotropy in the ground and excited states of [Gd2@C78]− and [Gd2@C80]−
2017
The magnetic properties and electronic structure of the ground and excited states of two recently characterized endohedral metallo-fullerenes, [Gd2@C78]- (1) and [Gd2@C80]- (2), have been studied by theoretical methods. The systems can be considered as [Gd2]5+ dimers encapsulated in a fullerene cage with the fifteen unpaired electrons ferromagnetically coupled into an S = 15/2 high-spin configuration in the ground state. The microscopic mechanisms governing the Gd-Gd interactions leading to the ferromagnetic ground state are examined by a combination of density functional and ab initio calculations and the full energy spectrum of the ground and lowest excited states is constructed by means …
Solution- and gas-phase study of binding of ammonium and bisammonium hydrocarbons to oxacalix[4]arene carboxylate
2023
Oxacalixarenes represent a distinctive class of macrocyclic compounds, which are closely related to the parent calixarene family, offering binding motifs characteristic of calixarenes and crown ethers. Nevertheless, they still lack extensive characterization in terms of molecular recognition properties and the subsequent practical applicability. We present here the results of binding studies of an oxacalix[4]arene carboxylate macrocycle toward a variety of organic ammonium cationic species. Our results show that the substituents attached to the guest ammonium compound largely influence the binding strengths of the host. Furthermore, we show that the characteristic binding pattern changes up…
UV laser induced photolysis of glycolic acid isolated in argon matrices
2021
The photochemistry of matrix-isolated glycolic acid, induced by UV light, was studied by FTIR spectroscopy and B3LYPD3/6-311++G(3df,3pd) calculations. Several decomposition pathways were found to take place upon 212 nm and 226 nm wavelengths irradiation. A number of complexes formed between photoproducts were identified, among them those of formaldehyde with water, carbon monoxide and carbon dioxide as well as the H2O-CO complexes. The structure and spectroscopic assignment of the photoproducts were made comparing the experimental results with the theoretical predictions and available literature data. The observed formation of different complexes indicates various pathways for their formati…
Scalable Constant pH Molecular Dynamics in GROMACS
2022
Molecular dynamics (MD) computer simulations are used routinely to compute atomistic trajectories of complex systems. Systems are simulated in various ensembles, depending on the experimental conditions one aims to mimic. While constant energy, temperature, volume, and pressure are rather straightforward to model, pH, which is an equally important parameter in experiments, is more difficult to account for in simulations. Although a constant pH algorithm based on the λ-dynamics approach by Brooks and co-workers [Kong, X.; Brooks III, C. L. J. Chem. Phys.1996, 105, 2414–2423] was implemented in a fork of the GROMACS molecular dynamics program, uptake has been rather limited, presumably due to…
Intra- vs Intermolecular Aurophilic Contacts in Dinuclear Gold(I) Compounds: Impact on the Population of the Triplet Excited State.
2022
Two series of dinuclear gold(I) complexes that contain two Au–chromophore units (chromophore = dibenzofurane or dimethylfluorene) connected through a diphosphane bridge that differs in the flexibility and length (diphosphane = dppb for 1,4-bis(diphenylphosphino)butane, DPEphos for bis[(2-diphenylphosphino)phenyl]ether, xanthphos for 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, and BiPheP for 2,2′-bis(diphenylphosphino)-1,1′-biphenyl) have been synthesized and structurally characterized. Their photophysical properties have been carefully investigated, paying attention to the role of the presence, or absence, of aurophilic contacts and their nature (intra- or intermolecular character). Th…
Binding of ion pairs and neutral guests by aryl-extended meso‑p-hydroxyphenyl calix[4]pyrrole : The interplay between three binding sites
2023
An aryl-extended calix[4]pyrrole with four meso‑p-hydroxyphenyl substituents was investigated as a host for chloride, acetate, and benzoate anions. Crystal structures of pyridinium and imidazolium chloride complexes were obtained in which chloride ions are hydrogen bonded exo-cavity to the upper rim hydroxyl groups, and the aromatic cations are bound to the shallow cavity of the host. Furthermore, the calix[4]pyrrole formed a hydrogen bonded dimeric capsule templated by inclusion of adiponitrile guest in the endo-cavity binding site. NMR titrations revealed the preference of the OH groups of the host to bind anionic guests in solution. Benzoate anion had the highest binding constant (4 700 …
Suitability of Phytosterols Alongside Fatty Acids as Chemotaxonomic Biomarkers for Phytoplankton
2016
The composition and abundance of phytoplankton is an important factor defining ecological status of marine and freshwater ecosystems. Chemotaxonomic markers (e.g., pigments and fatty acids) are needed for monitoring changes in a phytoplankton community and to know the nutritional quality of seston for herbivorous zooplankton. Here we investigated the suitability of sterols along with fatty acids as chemotaxonomic markers using multivariate statistics, by analyzing the sterol and fatty acid composition of 10 different phytoplankton classes including altogether 37 strains isolated from freshwater lakes. We were able to detect a total of 47 fatty acids and 29 sterols in our phytoplankton sampl…
Helix Inversion Controlled by Molecular Motors in Multistate Liquid Crystals.
2020
Unravelling the rules of molecular motion is a contemporary challenge that promises to support the development of responsive materials and is likely to enhance the understanding of functional motion. Advances in integrating light‐driven molecular motors in soft matter have led to the design and realization of chiral nematic (cholesteric) liquid crystals that can respond to light with modification of their helical pitch, and also with helix inversion. Under illumination, these chiral liquid crystals convert from one helical geometry to another. Here, a series of light‐driven molecular motors that feature a rich configurational landscape is presented, specifically which involves three stable …
Synthesis, X-ray structure, Hirshfeld analysis, and DFT studies of a new Pd(II) complex with an anionic s-triazine NNO donor ligand
2020
A new Pd(II) complex, [Pd(Triaz)Cl], with the hydrazono-s-triazine ligand, 2,4-di-tert-butyl-6-((2-(4-morpholino-6-(phenylamino)-1,3,5-triazin-2-yl)hydrazono)methyl)phenol, was synthesized by the reaction of PdCl2 with the organic ligand (1:1) in acetone under isothermal conditions. The molecular structure of the [Pd(Triaz)Cl] complex was determined using FTIR and 1H NMR spectroscopic techniques, and single-crystal X-ray diffraction. Moreover, using Hirshfeld surface analysis, the percentages of the intermolecular interactions were determined. The obtained values were 60.6%, 11.6%, 8.1%, 3.6%, and 5.0% for the H⋯H, C⋯H, O⋯H, N⋯H, and Cl⋯H interactions, respectively. Among them, the O⋯H, C⋯H…
Poly(alkylidenimine) Dendrimers Functionalized with the Organometallic Moiety [Ru(η5-C5H5)(PPh3)2]+ as Promising Drugs Against Cisplatin-Resistant Ca…
2018
Here and for the first time, we show that the organometallic compound [Ru(&eta