Fast motion of molecular rotors in metal–organic framework struts at very low temperatures

The solid state is typically not well suited to sustaining fast molecular motion, but in recent years a variety of molecular machines, switches and rotors have been successfully engineered within porous crystals and on surfaces. Here we show a fast-rotating molecular rotor within the bicyclopentane–dicarboxylate struts of a zinc-based metal–organic framework—the carboxylate groups anchored to the metal clusters act as an axle while the bicyclic unit is free to rotate. The three-fold bipyramidal symmetry of the rotator conflicts with the four-fold symmetry of the struts within the cubic crystal cell of the zinc metal–organic framework. This frustrates the formation of stable conformations, allowing for the continuous, unidirectional, hyperfast rotation of the bicyclic units with an energy barrier of 6.2 cal mol−1 and a high frequency persistent for several turns even at very low temperatures (1010 Hz below 2 K). Using zirconium instead of zinc led to a different metal cluster–carboxylate coordination arrangement in the resulting metal–organic framework, and much slower rotation of the bicyclic units

Phytoremediation: an alternative tool towards clean and green environment

Wetlands being the most productive and ecologically sensitive and adaptive ecosystems are constantly being challenged with anthropogenic pressures due to their wide variety of services they provide to mankind. The vast expansions of human population and associated activities have put a tremendous amount of pressure on these naturally occurring resources. Uncontrolled discharge of effluents in water from various sources resulted into altered nature of the associated ecosystems giving rise to several health issues and problems. Hence, realising the urgent need of protecting these ecologically fragile ecosystems several adaptive measures have been taken. In this connection, it is found that the available conventional methods are not feasible on various grounds like their cost, their by-products, time frame, etc. Therefore, the use of plants emerged as the alternative and promising tool for safe and sustainable ecosystem supporting life.Sandhya Misra, and Krishna G. Misra