Vibrational spectra of 6-methyluracil, 6-methyl-2-thiouracil and their deuterated analogues

Experimental study on the thermochemistry of 2-thiouracil, 5-methyl-2-thiouracil and 6-methyl-2-thiouracil

“…On the basis of the structures determined for 5-methyl-2-thiouracil [63], 5-methyluracil [64,65], 6-methyl-2-thiouracil [66][67][68][69] and 6-methyluracil [68,70,71] we can find the influence of the oxygen substitution by the sulphur atom on the crystal structure. The hydrogen-bond network of 5-methyl-2-thiouracil is different from that in thymine, since it involves all the donor and acceptor atoms [63].…”

“…The substitution of an oxygen by a sulphur atom on C2 of 6-methyl-2-thiouracil results in a significant bond-length change only at the substitution site [68]. The C2@S bond (0.1662 nm) is longer than the C2@O one (0.1224 and 0.1234 nm for polymorphic forms I and II of 6-methyluracil, respectively).This distance C2@S in 6-methyl-2-thiouracil is shorter than that in 5-methyl-2-thiouracil.…”

“…A strong N1-HÁÁÁO4@C4 hydrogen bond of 0.2786 nm is formed in 6-methyl-2-thiouracil, yet the same O atom in the polymorphic form I of 6-methyluracil only forms a contact between N-H and two adjacent molecules (0.285 and 0.287 nm), leading to endless ribbons of planar molecules. The less electronegative S atom is not involved in hydrogen-bonding because the distance N3-HÁÁÁS@C2 is about 0.3418(4) nm [67,68]. Oxygen atoms, being more electronegative than sulphur atoms are expected to create more advantageous, stronger and shorter hydrogen bonds.…”

Effect of the sulfur atom on S2 and S4 positions of the uracil ring in different DNA:RNA hybrid microhelixes with three nucleotide base pairs

“…Although the nucleobases with sulfur appear with the same distribution of acceptors and donors groups that the natural nucleobases with oxygen, however, the thiobases cause specific changes in the properties. Thus, a large number of thiouracil derivatives have been used in numerous pharmacological applications, and also attract attention for anti‐HIV, heart diseases treatments, and others . Nucleosides containing 2‐thiouracil are modified units that appear essentials in natural and synthetic nucleic acids .…”

Synthesis, X-ray Diffraction, Thermogravimetric and DFT Analyses of Pyrimidine Derivatives

“…Indeed, some of them are the basic constituents of DNA and RNA, and play an important role in the constitutional properties of nucleic acids. Pyrimidine-derived biomolecules have received much attention from spectroscopists, drug, clinical, and industrial researchers because of their therapeutic importance [1,2,3,4,5,6,7,8,9]. Barbiturates (barbituric acid derivatives) are a class of central nervous system depressants, [10] utilized as sedatives, sleeping agents, hypnotics, anxiolytics, anticonvulsants, and anesthetics [7].…”