Crystal structure, intermolecular interactions, charge-density distribution and ADME properties of the acridinium 4-nitrobenzoate and 2-amino-3-methylpyridinium 4-nitrobenzoate salts: a combined experimental and theoretical study.

Acridines are a class of bioactive agents which exhibit high biological stability and the ability to intercalate with DNA; they have a wide range of applications. Pyridine derivatives have a wide range of biological activities. To enhance the properties of acridine and 2-amino-3-methylpyridine as the active pharmaceutical ingredient (API), 4-nitrobenzoic acid was chosen as a coformer. In the present study, a mixture of acridine and 4-nitrobenzoic acid forms the salt acridinium 4-nitrobenzoate, C13H10N+·C7H4NO4- (I), whereas a mixture of 2-amino-3-methylpyridine and 4-nitrobenzoic acid forms the salt 2-amino-3-methylpyridinium 4-nitrobenzoate, C6H9N2+·C7H4NO4- (II). In both salts, protonation takes place at the ring N atom. The crystal structure of both salts is predominantly governed by hydrogen-bond interactions. In salt I, C-H...O and N-H...O interactions form an infinite chain in the crystal, whereas in salt II, intermolecular N-H...O interactions form an eight-membered R22(8) ring motif. A theoretical charge-density analysis reveals the charge-density distribution of the inter- and intramolecular interactions of both salts. An in-silico ADME analysis predicts the druglikeness properties of both salts and the results confirm that both salts are potential drug candidates with good bioavailability scores and there is no violation of the Lipinski rules, which supports the druglikeness properties of both salts. However, although both salts exhibit drug-like properties, salt I has higher gastrointestinal absorption than salt II and hence it may be considered a potential drug candidate.

A novel two-staged single-visit treatment of a maxillary central incisor with complicated crown-root fracture with additional horizontal mid-root fracture - A case report with a 5-year follow-up.

A concomitant complicated crown-root fracture (CCRF) and horizontal root fracture (HRF) is rarely reported in literature. This report proposes a two-staged single-visit treatment to salvage maxillary central incisor with coexisting CCRF and HRF. A female patient with CCRF with additional HRF (AHRF) of maxillary left central incisor was successfully managed with a novel two-staged treatment strategy. Stage 1 included stabilization of AHRF followed by fragment reattachment in Stage 2 of the treatment. At 5 years of followup, clinical examinations revealed no mobility or discoloration of the reattached fragment with satisfactory periodontal condition. Conebeam computed tomography revealed accurate approximation of reattached fragment to the remaining tooth and the HRF showed type II (connective tissue) healing pattern. This case report concludes that two-staged treatment can be performed as an alternative treatment to invasive therapy like extraction.

Insights on structure and interactions of 2-amino-4-methoxy-6-methylpyrimidinium salts with 4-aminosalicylate and 5-chlorosalicylate: a combined experimental and theoretical charge-density analysis.

The proton-transfer complexes 2-amino-4-methoxy-6-methylpyrimidinium (2A4M6MP) 4-aminosalicylate (4AMSA), C6H10N3O+·C7H6NO3-, I, and 5-chlorosalicylate (5ClSA), C6H10N3O+·C7H4ClO3-, II, were synthesized by slow evaporation and crystallized. The crystal structures of both I and II were determined by single-crystal X-ray structure analysis. The crystal structures of both salts exhibit O-H...O, N-H...O, N-H...N and C-H...O interactions in their crystals. The 4AMSA and 5ClSA anions in combination with the 2A4M6MP cations form distinct synthons, which are represented by the graph-set notations R22(8), R42(8) and R22(8). Furthermore, the ΔpKa values were calculated and clearly demonstrate that 2A4M6MP is a good salt former when combined with carboxylic acids. Hirshfeld surface analysis was used to quantify the weak and strong interactions in the solid state, and energy framework calculations showed the stability of the hydrogen-bonding interactions. QTAIM (quantum theory of atoms in molecules) analysis revealed the nature of the chemical bonding in I and II, and the charge-density distribution in the intermolecular interactions in the crystal structures.