The synthesis of chiral metal-organic frameworks (MOFs)i sh ighly relevant for asymmetric heterogenous catalysis, yet very challenging. Chiral MOFsw ith MOF-74 topology were synthesised by using post-synthetic modification with proline. Vibrational circular dichroism studies demonstrate that prolinei st he source of chirality.T he solvents used in the synthesis play ak ey role in tuning the loading of proline and its interaction with the MOF-74 framework. In N,N'-dimethylformamide, proline coordinates monodentate to the Zn 2 + ions withint he MOF-74 framework, whereasi ti s only weakly bound to the frameworkw hen using methanol as solvent. Introducing chirality within the MOF-74f ramework also leads to the formation of defects, with both the organic linkera nd metal ions missing from the framework. The formationo fd efects combined with the coordination of DMF and prolinew ithin the framework leads to ap ore blockinge ffect. This is confirmed by adsorption studies and testingo ft he chiral MOFs in the asymmetric aldol reaction betweenacetone and para-nitrobenzaldehyde.

A detailed analysis of the computed structure, energies, vibrational absorption (VA) and circular dichroism (VCD) spectra of 30 low-energy conformers of dehydroquinidine reveals the existence of families of pseudo-conformers, the structures of which differ mostly in the orientation of a single O-H bond. The pseudo-conformers in a family are separated by very small energy barriers (i.e., 1.0 kcal mol(-1) or smaller) and have very different VCD spectra. First, we demonstrate the unreliable character of the Boltzmann factors predicted with DFT. Then, we show that the large differences observed between the VCD spectra of the pseudo-conformers in a family are caused by large-amplitude motions involving the O-H bond, which trigger the appearance/disappearance of strong VCD exciton-coupling bands in the fingerprint region. This interplay between exciton coupling and large-amplitude-motion phenomena demonstrates that when dealing with flexible molecules with polar bonds, vibrational averaging of VCD spectra should not be neglected. In this regard, the dehydroquinidine molecule considered here is expected to be a typical example and not the exception to the rule.

Opening a prototypical chromene compound using UV radiation and witnessing the evolution of the photoactivated structures with infrared light.