Overview

This course would highlight the concepts and applications of widely used experimental technique of X-ray crystallography. The could would take the students through the lane of crystallographic symmetry to the structure determination and refinement of crystal structures using x-ray diffraction. Any experimental organic or inorganic chemist would be benefited from this course.INTENDED AUDIENCE :PhD students and 2nd year M.Sc studentsPREREQUISITES :Basic knowledge about molecular symmetryINDUSTRY SUPPORT :Pharmaceutical industry

Syllabus

Week 1 : Introduction, 1D symmetry, Concept of 2D symmetry and lattices, notations of symmetry elements, space groups in 2D, 3D lattices, 32 point groups and their notations, crystal systems and Bravais lattices.Week 2 : Stereographic projections, Laue symmetry; glide planes, screw axes and their notations, space groups, equivalent points, space group symmetry diagrams etc.Week 3 : Miller Indices, crystallographic planes and directions, close pack structures, linear density, planar density, Miller-Bravais indices for hexagonal systems, various ceramic structures (NaCl, ZnS, CaF2, CsCl etc.), octahedral and tetrahedral sites etc.Week 4 : What are X-rays, generation and classification of X-ray, X-ray sources, diffraction of X-rays, Bragg's law.The reciprocal lattice, reciprocal relationship, Bragg's law in reciprocal space, Ewald's sphere and sphere of reflectionWeek 5 : Methods of crystal growth, identification of phases and morphologies, in-situ cryo crystallization, crystal growth under external stimuli etc.Week 6 : Data collection strategies, Laue Method, Oscillation, rotation and precession methods. L-P corrections, structure factor, scaling, interpretation of intensity data, temperature factor, symmetry from intensity statisticsWeek 7 : Structure factor and Fourier synthesis, Friedel's law; exponential, vector and general forms of structure factor, determination of systematic absences for various symmetry or lattice centering, FFT, Anomalous scattering and absolute configuration.Week 8 : Phase problem, Direct Methods, structure invariants and semi invariants, probability methods, Phase determination in practice, Patterson Methods, Patterson Symmetry, completion of structure solution, ï „F synthesis.Week 9 : Refinement by Fourier synthesis, refinement by ï „F synthesis, Refinement by least squares method, weighting functions, Goodness-of-Fit (GOF) parameter, treatment of non-hydrogen atoms, and treatment of hydrogen atoms, treatment of disordered structures.Week 10 : Crystal selection, indexing of crystals, data collection, data reduction, space group determination, structure solution and refinement using SHELXS97 and SHELXL97, introduction to crystallographic packages (APEX II suite, OLEX2, WinGx, PLATON) and IUCr validation of the dataWeek 11 : Methodology, geometrical basis of powder X-ray diffraction, applications of PXRD: determination of accurate lattice parameters, identification of new/unknown phases, applications in pharmaceutical industry.Week 12 : Applications of powder X-ray diffraction: Structure determination from PXRD and Reitveld method for structure refinement, indexing of PXRD, handling of PXRD using DASH.