http://rdu.iquimica.unam.mx/handle/20.500.12214/37 Fri, 13 Mar 2026 00:40:03 GMT 2026-03-13T00:40:03Z http://rdu.iquimica.unam.mx/handle/20.500.12214/1315 Title: Tailoring the cavities of hydrogen-bonded amphidynamic crystals using weak contacts: towards faster molecular machines Author: Braulio Rodríguez-Molina Contributor: Gabriel Merino Abstract: This work describes the use of C–H/F–C contacts in the solid-state from the stator towards the rotator to fine-tune their internal motion, by constructing a set of interactions that generate close-fitting cavities in three supramolecular rotors 1–3I. The crystal structures of these rotors, determined by synchrotron radiation experiments at different temperatures, show the presence of such C–H/F–C contacts between extended carbazole stators featuring fluorinated phenyl rings and the 1,4-diazabicyclo[2.2.2] octane (DABCO) rotator. According to the 2H NMR results, using deuterated samples, and periodic density functional theory computations, the rotators experience fast angular displacements (preferentially 120 jumps) due to their low rotational activation energies (Ea 1⁄4 0.8–2.0 kcal mol 1). The higher rotational barrier for 1 (2.0 kcal mol 1) is associated with a larger number of weak C–H/F–C contacts generated by the stators. This strategy offers the possibility to explore the correlation among weak intermolecular forces, cavity shape, and internal dynamics, which has strong implications in the design of future fine-tuned amphidynamic crystals. Fri, 01 Jan 2021 00:00:00 GMT http://rdu.iquimica.unam.mx/handle/20.500.12214/1315 2021-01-01T00:00:00Z http://rdu.iquimica.unam.mx/handle/20.500.12214/1303 Title: Expected and unexpected products in half curcuminoid synthesis: crystal structures of but-3-en-2-ones and 3-methylcyclohex-2-enones Author: Raul G. Enriquez Contributor: William Meza Morales Abstract: The expected (E)-but-3-en-2-ones compounds I and II (half curcuminoids) were obtained by the Claisen–Schmidt reaction between aldehydes 3,4-dimethoxybenzaldehyde or 4-nitrobenzaldehyde with acetone. Concomitantly, 3-methylcyclohex-2-enones compounds III and IV arose from an un- expected reaction of but-3-en-2-ones in the cascade reaction of a Michael-type addition of a second molecule of acetone followed by Robinson annulation under strong basic conditions. Both enones exhibit the (E)-configuration, compound I displays s-trans conformation, whereas compound II exhibits conformational disorder as solid solution of s-cis and s-trans conformations. The related 3-methylcyclohex-2-enones exhibit envelope conformation. Compound III constitutes an example of the rarest case of racemic solid solution (pseudoracemate), where a lack of chiral discrimination with respect to the two enantiomers leads to an enantiomeric disorder of a racemic mixture with different occupancies at the reference site. Due to the lack of strong hydrogen-bond donors in all compounds, the crystal packing is mainly stabilized by weak intermolecular C-H···O interactions between the molecules. The present work provides a new perspective on the search for by-products normally overlooked in Claisen–Schmidt condensations. Fri, 01 Jan 2021 00:00:00 GMT http://rdu.iquimica.unam.mx/handle/20.500.12214/1303 2021-01-01T00:00:00Z http://rdu.iquimica.unam.mx/handle/20.500.12214/1296 Title: Synthesis of novel pyrroloazepinones by Schmidt expansions of 6-indolones Author: ROBERTO MARTINEZ Abstract: New derivatives of pyrroloazepinones were synthesized. The synthesis route consisted of three stages: the formation of a dimedone-derived tricarbonyl compound, the formation of a pyrrole ring resulting from the use of the Paal-Knorr method to generate tetrahydroindole-6-ones, and the expansion of the ketone by following the Schmidt method to generate lactams. The obtained 6-indolones were used to generate new derivatives: the pyrrolo[2,3-c]azepin-6-one and the pyrrolo[2,3-d]azepin-7-one ring systems. The synthesized pyrroloazepinones were evaluated for inhibitory activity in cancer cell lines and they did not show activity and cytotoxic effects on the non-tumor cells HEK239, with IC50 ≥ 215 ± 5.41 μM. Wed, 01 Jan 2020 00:00:00 GMT http://rdu.iquimica.unam.mx/handle/20.500.12214/1296 2020-01-01T00:00:00Z http://rdu.iquimica.unam.mx/handle/20.500.12214/1294 Title: Multiple rotational rates in a guest-loaded, amphidynamic zirconia metal–organic framework Author: Braulio Rodríguez-Molina Contributor: Fernando Uribe-Romo Abstract: Amphidynamic motion in metal–organic frameworks (MOFs) is an intriguing emergent property, characterized by high rotational motion of the phenylene rings that are embedded within an open, rigid framework. Here, we show how the phenylene rings in the organic linkers of the water stable MOF PEPEP-PIZOF-2 exhibit multiple rotational rates as a result of the electronic structure of the linker, with and without the presence of highly interacting molecular guests. By selective 2H enrichment, we prepared isotopologues PIZOF-2d4 and PIZOF-2d8 and utilized solid-state 13C and 2H NMR to differentiate the dynamic behavior of specific phenylenes in the linker at room temperature. A difference of at least one order of magnitude was observed between the rates of rotation of the central and outer rings at room temperature, with the central phenylene ring, surrounded by ethynyl groups, undergoing ultrafast 180 jumps with frequencies higher than 10 MHz. Moreover, loading tetracyanoquinodimethane (TCNQ) within the pores produced significant changes in the MOF's electronic structure, but very small changes were observed in the rotational rates, providing an unprecedented insight into the effects that internal dynamics have on guest diffusion. These findings would help elucidate the in-pore guest dynamics that affect transport phenomena in these highly used MOFs. Wed, 01 Jan 2020 00:00:00 GMT http://rdu.iquimica.unam.mx/handle/20.500.12214/1294 2020-01-01T00:00:00Z