Chemistry_in_21st_Century二十一世纪的化学.ppt

Chemistry in 21st Century National Centre for Catalysis Research INDIAN INSTITUTE OF TECHNOLOGY MADRAS APRIL 2010 Coverage and Reasons Bonding in molecules Conventional concepts of bonding has to undergo change – Why? Behaviour of molecules and reactivity of molecules – what is so special selectivity? Geometry of the molecules, manifestations of molecules – functioning of molecules. Architecture in solids – transport restrictions Electrochemistry turns chemistry to be fully green Behaviour of electrons – responsible for the science that is usually generated Nuclear structure – evolution period and also energy conversion process 20th Century Chemistry It was a silent revolution Ammonia synthesis provided a means for food FCC operation brought engineering marvel Zeolites and solid state materials – revolutionized electronic industry Super conductors – energy concept changed colours Water will it be another wonder molecule this century WEAK INTERACTIONS Assembly appears to be the order these days – these assembly can arise out of weak interactions Weak interactions may be hydrogen bonding, van der waals forces and simple over lap of the least amount of charge cloud. Assembly assumes particular geometries, like helical structure, nano-coils, nano-twisted wires and many others – these resemble the bio-molecules Aggregation is it universal? Having seen single molecules and their behaviour one has to turn the attention to aggregates. Why aggregates, it appears it is the natures way of preserving and fostering things – trees, plants, animals, human beings everything live as aggregates and care for the total aggregated assemblies and not for the individual species. Aggregation The existence of single molecules can be understood from the point of view of minimization of free energy Aggregates how do they minimize the energy? What is the driving force for this aggregation? What is the type of interactions present in aggregation? Weak bonding is the cause for aggre