The crystal structure of 6-amino-5-carboxypyridin-1-ium pentaiodide monohydrate C6H9I5N2O3

C6H9I5N2O3, triclinic, P1¯ (no. 2), a = 7.4851(5) Å, b = 9.6056(6) Å, c = 12.4084(7) Å, α = 109.119(3)°, β = 99.341(3)°, γ = 92.334(3)°, V = 827.53(9) Å3, Z = 2, R gt (F) = 0.0234, wR ref (F 2) = 0.0449, T = 150.0 K.

New Crystal Forms for Biologically Active Compounds. Part 2: Anastrozole as N-Substituted 1,2,4-Triazole in Halogen Bonding and Lp-π Interactions with 1,4-Diiodotetrafluorobenzene

For an active pharmaceutical ingredient, it is important to stabilize its specific crystal polymorph. If the potential interconversion of various polymorphs is not carefully controlled, it may lead to deterioration of the drug’s physicochemical profile and, ultimately, its therapeutic efficacy. The desired polymorph stabilization can be achieved via co-crystallization with appropriate crystallophoric excipients. In this work, we identified an opportunity for co-crystallization of anastrozole (ASZ), a well-known aromatase inhibitor useful in second-line therapy of estrogen-dependent breast cancer, with a classical XB donor, 1,2,4,5-tetrafluoro-3,6-diiodobenzene (1,4-FIB). In the X-ray structures of ASZ·1.5 (1,4-FIB) co-crystal, different non-covalent interactions involving hydrogen and halogen atoms were detected and studied by quantum chemical calculations and QTAIM analysis at the ωB97XD/DZP-DKH level of theory.

Optimization and comparison of statistical tools for the prediction of multicomponent forms of a molecule: the antiretroviral nevirapine as a case study

A methodology is proposed to assess the propensity to obtain multicomponent forms of an API based on the combination of modified statistical analytical tools to order the possible co-formers in a ranking index.

New Crystal Forms for Biologically Active Compounds. Part 1: Noncovalent Interactions in Adducts of Nevirapine with XB Donors

Stabilization of specific crystal polymorphs of an active pharmaceutical ingredient is crucial for preventing uncontrollable interconversion of various crystalline forms, which affects physicochemical properties as well as physiological activity. Co-crystallization with various excipients is an emerging productive way of achieving such stabilization in the solid state. In this work, we identified an opportunity for co-crystallization of antiviral drug nevirapine (NVP) with a classical XB donor, 1,2,4,5-tetrafluoro-3,6-diiodobenzene (1,4-FIB), as well as 1,3-diiodobenzene (1,3-DIB), which has been seldom employed as an XB donor to date. In the X-ray structures of NVP·1,4-FIB and NVP·1,3-DIB co-crystals, different hydrogen and halogen bonding modes were detected and further investigated via DFT calculations as well as topological analysis of the electron density distribution within the framework of the QTAIM method at the M06/DZP-DKH level of theory. Estimated energies of these supramolecular contacts vary from 0.6 to 5.7 kcal/mol.