The integration of luminescence and chirality in easy-scalable metal-organic frameworks gives rise to the development of advanced luminescent sensors. To date, the synthesis of chiral metal-organic frameworks is poorly predictable and their chirality primarily originates from components that constitute the frameworks. By contrast, the introduction of chirality into the pores of metal-organic frameworks has not been explored to the best of our knowledge. Here, we demonstrate that chirality can be introduced into an anionic Zn-based metal-organic framework via simple cation exchange, yielding dual luminescent centers comprised of the ligand and Tb3+ ions, accompanied by a chiral center in the pores. This bifunctional material shows enantioselectivity luminescent sensing for a mixture of stereoisomers, demonstrated for Cinchonine and Cinchonidine epimers and amino alcohol enantiomers, from which the quantitative determination of the stereoisomeric excess has been obtained. This study paves a pathway for the design of multifunctional metal-organic framework systems as a useful method for rapid sensing of chiral molecules.
Aims. In this paper, we present the simulations for the primordial blue stragglers in the old open cluster M 67 based on detailed modelling of the evolutionary processes. The principal aim is to discuss the contribution of mass transfer between the components of close binaries to the blue straggler population in M 67. Methods. First, we followed the evolution of a binary of 1.4 M +0.9 M . The synthetic evolutionary track of the binary system revealed that a primordial blue straggler had a long lifetime in the observed blue straggler region of color-magnitude diagram. Second, a grid of models for close binary systems experiencing mass exchange were computed from 1 Gyr to 6 Gyr in order to account for primordial blue-straggler formation in a time sequence. Based on such a grid, Monte-Carlo simulations were applied for the old open cluster M 67. Results. Adopting appropriate orbital parameters, 4 primordial blue stragglers were predicted by our simulations. This was consistent with the observational fact that only a few blue stragglers in M 67 were binaries with short orbital periods. An upper boundary of the primordial blue stragglers in the color-magnitude diagram (CMD) was defined and could be used to distinguish blue stragglers that were not formed via mass exchange. Using the grid of binary models, the orbital periods of the primordial BSs could be predicted. Conclusions. Compared with the observations, it is clear that the mechanism discussed in this work alone cannot fully predict the blue straggler population in M 67. There must be several other processes also involved in the formation of the observed blue stragglers in M 67.
Porosity is a fundamental property of metalorganic frameworks (MOFs). However, the role of the pore size has always been underestimated in MOF-based luminescent sensors for enantioselective sensing. The construction of isoreticular MOFs (IRMOFs) with variable pore sizes and the synergy between chirality and luminescence is challenging. Herein, a general strategy was developed to introduce chirality into two well-known IRMOF-74 analogs with nanochannels of identical shapes but different pore sizes by functionalizing the open metal site under mild conditions. To enhance the detection accuracy, a second luminescent center was introduced into the IRMOF-74 system to achieve ratiometric sensing. The two bifunctionalized IRMOF-74 compounds exhibited pore-size-dependent sensing performance for enantiomers. This study not only provides a convenient method to construct chiral MOFs as advanced sensing materials but also reveals the fundamental of the pores in MOF-based luminescent sensors.
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