The second part X-ray Diffraction (XRD) Powder X-ray - Book Report/Review Example

Task: The second part X-ray Diffraction (XRD) Powder X-ray Powder X-ray diffraction is among the primary methods, which are used by solid-state chemists and mineralogists to examine physic-chemical build-up of solids, which are unknown to them. The data is denoted in a group of single-phase X-ray powder diffraction forms of three strong D values in table form (Khan 24). The tables include mineral name, relative intensity (I/I) and interplanar spacing. The method takes a sample material and places a sample of powder in a holder. Illumination of the sample then follows with x-rays of an inflexible wavelength. Recording of intensity of the reflected radiation takes place using a goniometre. Analysis of the angle of reflection enables computing of the inter-atomic spacing (D value in Angstrom units is -10 raised to 8cm). Intensity in this case intensity is assessed to discriminate various spacing. The results are used to find possible matches. The diagram below shows Powdered X-ray in action. Principles The diffraction line profiles observed in the powder diffraction scheme are supplies of intensities, which are defined by various parameters. First the reflection angle which has the maximum intensity that is related to spacing of the lattice of the diffracting flat surface together with the wavelength. Braggs law state that ??= 2dsin?.seondly, distribution of the dispersion, at an integral and half-maximum breadth. Thirdly, the shape of the line is also a factor and lastly intensity integration which is proportional to the square of the factor amplitude. Single-Crystal X-ray Single-crystal x-ray diffraction is a technique that gives details about internal lattice of crystalline matter without any destructive effects. The technique reveals bond angles, cell dimensions, bond-lengths and details related to site ordering. This technique has a direct relationship with single-Crystal refinement (Khan 34). In single-Crystal technique information is generated from the X-ray analysis, interpreted and refined so as to get the original crystal structure. Principles Laue Von Max discovered that crystalline matter act in three-dimensional diffraction. The gratings for X-ray wavelength are the same as the spacing planes in the crystal lattice. Currently X-ray diffraction is a wide spread technique used for studying atomic spacing and crystal structures. The X-ray diffraction has a base on interference of single chromatic X-rays constrictively together with crystalline samples. Production of X-rays takes place at the cathode ray tube. The rays are then filtered to generate monochromatic radiations. They are collimated to allow concentration to take place and lastly, they are directed towards the sample. The relation between the sample and the X-rays generates constructive interference, together with a diffracted ray if the conditions are favorable according to Braggs law, (n?=2d sin?). The law relates electromagnetic wavelength radiation with the diffraction angle bearing into consideration of the lattice spacing in the crystalline sample. Detection of X-rays takes place and then processed before counting them. Changing incident rays geometrically, orientation of the crystal at the centre together with the detector makes it possible to identify all diffraction directions of the rays (Graham & Eddie 56). All the techniques have their base on the production of X-rays inside the X-ray tube. The X-rays are directed to the sample then the diffracted rays are put together. All diffractions base on the angle between diffracted and incident rays. In this context, single-Crystal and powder diffraction differ in instrumentation. The diagram below shows the original single-crystal X-ray. Applications and uses Most of the x-ray applications base on their ability to penetrate through a material. The ability varies within different objects. For instance, X-rays can penetrate easily through flesh and wood and penetrate less in more dancer substances like bones. The power for the X-ray to penetrate also depends on the energy of the X-ray. X-rays that penetrate more are known as hard X-rays and they have high frequency thus having great energy. On the other hard X-rays that have les penetration power are known as soft X-rays. They have less energy compared to hard X-rays. When X-rays pass through the body, they give an image of the structure of the interior parts when they hit a fluorescent screen or a photographic plate. The shadows darkness depend on the opacity in different parts of the body (Khan 67). X-rays can be very useful in making photographs. These photographs are referred to as skiagraphs or radiographs. Radiography has a range of use in many industries and medicine. In both areas it is useful in nondestructive testing and diagnosis of products to detect any defects. Fluoroscopy has its base on this technique where by photographic plate can be replaced with a fluorescent screen. It has many advantages compared to radiography in terms of cost and time. X-rays are used with computers to produce cross sectional images of the inner parts of the body in computerized axial tomography. Thermal Analysis Differential Scarnning Calorimetry and Thermo-Gravimetric This technique is used to give characters to thermophysical properties of polymers. DSC can enable measuring of important thermoplastic qualities, which include melting point, melting heat, percent crystallinity, plasticizers among others. In this technique, the amount of heat is needed to increase temperatures of the sample and the references measured as a temperature function. The reference and the sample are maintained at almost the same temperature during the experiment. In most cases, the program of the temperature for analyzing is designed in a way that the temperature increases linearly to the time function (Graham & Eddie 78). The reference must have a well-defined capacity of heat over a wide range of temperature to be scarned. The basis underlying the technique is, when the sample moves on a physical transformation, like phase transitions, less or more heat will be required to it than the reference in order to maintain same temperature in both of them. It does not matter whether less or more heat should flow to the sample it depends with the process, endothermic or exothermic. Thermogravimetric Analysis (TGA) thermogravimetric analysis is a technique that looks at changes in weight of materials depending on temperature or time but under a controlled environment. Its principles include measurement of matter’s thermal composition and stability. The thermogravimetric analysis is extensively used in all the phases of research process. It also observes quality control product operations. TGA instruments give the Q50000IR, Q50, and numerous DSC/TGAQ600 that can meet different requirements of the researcher academic instructors and quality analysts’ control. TGA measurement gives important information, which can help in selecting for specific end-use applications. It can also provide valuable data for predicting the performance of a product and make improvement on its quality. It is most important in the following areas of matter: thermal stability, oxidative stability, estimation of lifetime of products, kinetics relating to decomposition among others. Typical TGA results showing thermal degradation in a Nylon 6,6 product (FTIR) Fourier Transform Infrared Spectroscopy This is a powerful tool that help in identifying different types of bonding in different molecules through production of infrared absorption spectrum, which is the same as a molecular in other words fingerprint. Principles Molecular bonds usually vibrate at different frequencies that depend on the type of bonds and the type of element involved. Every bond has specific frequencies under which it can vibrate. Quantum mechanics reveal that the frequencies relate to ground state or lowest frequency and various states that are exited or high frequencies (Graham & Eddie 90). This one way can cause frequencies in a molecular to vibrate leading to increase to excite thus making the bond to absorb light energy. For any transition between two states, light energy that is determined by wave length should be equal to the difference between two states normally ground state (E0) and the first excited state (E1). The energy that corresponds to the transition between molecular vibration states is normally 1-10kilocalories/molecule that corresponds to infrared proportion of electromagnetic spectrum. Fourier microscope Third Part Supramolecular Chemistry Supramolecular chemistry is a branch of chemistry that deals with the study of noncovalent interactions between and within different molecules. Most ancient chemists used to study the manner in which ions and atoms are joined together by use of ionic and covalent bonds. They also made studies on how the bonds form and break during chemical reactions. On the other hand , supramolecular chemistry deals with the weak reversible noncovalent relations. For example, metal coordination, hydrogen bonding, van der Waals forces, electronic effects, hydrophobic forces and pi-pi interactions (Day et al. 34). History of Supramolecular Chemistry Intermolecular existence was first identified by Diderik Van der Waals in the eighteen seventy-three. However this branch of chemistry has its base from Nobel laureate Hermann Emil Fischer. Fischer came up with a suggestion that relations between enzymes with their substrates have a form of lock and key the concept that has been valuable in providing explanation of molecular identification together with host-guest chemistry. During the twentieth century, understanding of noncoverlent bonds was increasing gradually in details with the description of hydrogen bonding by Rodebush and Latimer in the year 1920. Application of the principles enabled understanding of different biological macromolecules together with the involved processes. For example, the crucial breakthrough, which enabled elucidation of double-helical form of the DNA, took place after realizing that DNA is made up of two unattached strands of nucleotides joined by hydrogen bonds. Using of noncovalent bonds is important since it enables separation of the strands to be used as templates for other new double-stranded DNA molecules. Concurrently, chemists started to realize ant make studies on synthetic structures like micro emulsions and micelles that involves non-covalent relations. In due course, chemists took the concepts and applied in the synthetic schemes. They managed to break through in the year 1960s when Pedersen J. Charles synthesized crown ethers. Other researchers made a follow up on this work and made several important findings. They included Jean-Marie Lehn, Fitz Voltage and Donald Cream J., made significant entrance in the research process (Day et al. 45). They managed to synthesize the shape of the ion selective receptors. Vigorous research went on throughout 1980s at a high speed leading to emergence of various concepts like mechanically interlocked molecular architectures. The researchers who made great contributions towards identifying significant concepts had worn a Nobel Prize in 1987 to recognize their efforts in supramolecular chemistry. They developed the selective host guest in which the host molecule identifies and selectively joins to a certain guest. Supramolecular chemistry became more advanced in 1990s with the entrance of new players in the field like Stoddart Fraser James who developed machinery in molecular and highly technical self-assembled constructions. On the other hand, Willner Itamar developed sensors and techniques for electronic and biological interfacing. Photochemical and electrochemical motifs were integrated in supramolecular procedures to make increment in functionality. Additionally, the research at this period was directed towards areas of involving synthetic of self-replicating procedures and molecular data processing devices. Emerging of nanotechnology in science made a significant influence on the subject with construction block like nanoparticles, dendrimers and fullerenes. Concepts Molecular self-assembly Molecular self-assembly means either, folding of distinct molecules like polypeptides or formation of make-ups that involve two or more molecules by noncovalent relations. The methods can fall under molecular or intramolecular respectively. In this regard, the molecules are said to be self assemble since the buildings are shaped basing on molecules involved. This takes place without any effect from outside sources. It only requires that suitable environment. This process allows construction of huge constructions like micelles vesicles, liquid crystals and membranes. It has a basic principle for crystal engineering (Day et al. 67). Crystal Engineering In 1988, a high profile journal that revealed most scientists and scientists materials failed to predict crystal structures through prior chemical composition knowledge. One year later Gautam Desiraju came up with a book titled Crystal Engineering The Design of Organic Solids. The two events concurrently, became water washed moments for instant and fast development of crystal engineering that overlaps with minimum effect on crystal form prediction. Specifically crystal engineering looks at synthesis of latest classes of crystalline resources from first principles by a strategy which uses molecules as the Lego building blocks. Desiraju defined crystal engineering in 1989 as the understanding of intermolecular interactions in the context of crystal packing and utilization of such understanding in the design of new solids with desired physical and chemical properties (Ramenar et al. 78). This indicates that there was not a lot of interest and respect for crystal engineering in the earlier days. Most of the chemists during those days could have utilized the same knowledge to become oxymorons since crystals were thought to be nature abhors a vacuum. Additionally, unusual characteristics of crystals forms were explained as a way of being a result of effects of crystal packing. Crystal engineering has enabled rapid development of fresh class’s compound, which has contributed to realistic utility like polymers porous coordination, aka metal-organic frameworks (MOFs). Additionally, pharmaceutical co-crystals represent two of the active high-impact regions in chemistry today. Importantly, MOFs utilizes the knowledge in that ZnO4 tetrahedra are connected by benzene decarboxylate ligands. They form an extended 3D network that has accessible pores (Ramenar et al. 100). Co-crystals Anciently, solid structure selection method was limited to pharmaceutically free drug and legal salts. Basing on this choice, the structure with the best characteristics for the intended use was produced. Options in development during the research for the best solid structures are significantly increasing through co-crystal creativity of new chances for drug patent security. Distinctive Physic-chemical Characteristics Pharmaceutical co-crystal is made up of two or more properties, which are solids at normal temperature (Solvias 80). This definition can bring out debatable topics although it provides concrete differentiation from solvates or the other two-component schemes. The characterization thus gives provide a well-suited description of the new and possible solids structures for pharmaceutical functions. There is a difference in co-crystal and a salt in that, a proton is relocated from the acid to the functionality of a crystallization partner in the form of pKa, which gives a great difference between partners. In co-crystals transfer of partners do not take place as indicated in figure 1 below. In real sense, the situation is more technical in the manner that co-crystals and salts can exhibit polymorphism and form solvates. It becomes even more technical in the sense that co-crystals can be formed from a crystallization partner and salts. Co-crystals have several characteristics than salts or free drugs. The solid structure affects appropriate physico-chemical restrictions like chemical stability, the rate of dissolution of the drug, hygroscopicity and solubility that can come up with solids that have superior characteristics. Itraconazole is a well-documented case where by various carboxylic acid, which are co-crystals present high solubility and faster rate of dissolution of the drug than free drug. If bioavailability is mostly affected by solubility and dissolution, it can have momentous reputations and determine whether the compound is developed. Co-crystals’ physic-chemical difference from other forms of solids provide explanation why they have preference in some cases. Figure 1) Schematic overview of possible solid species, it should be noted that co-crystals such as salts can form solvates and also exhibit polymorphism. Importance of Co-crystals Co-crystal formation can be applied in different areas for several reasons. For instance, a neutral compound like an amorphous does not readily form salts. Crystallization of amorphous can take place to form a co-crystal than in the form of a free drug. Crystallization process works frequently by purifying the material that is starting the stage, which produces crystallizable batch of a free drug immediately after re-extraction (Solvias 90). The decision can be made on which crystalline structures to make between a co-crystalline and the free drug basing on the judgment of their physic-chemical characteristics. In some instances, co-crystals give the only chance for crystal generating which are important for single-crystal analysis. The results can be used to demonstrate the complete configuration of a chiral nonaligned compound. A three-phase Solvias Program of Crystals Salvias came up with a modular co-crystal plan comprising of three separate phases shown by the diagram 2 below. In phase, one the client defines the screening scope. This scope later determines the type of assortment of the possible co-crystal formers. For selection procedure, utilization of solvias’ own database must be observed. It considers physic-chemical limits, pharmaceutical approval, GRAS position and other several factors. After defining the relevant co-crystal formers, consultation with the client takes place and the screening phase begins. This is the second phase. Crystallization of co-crystals takes place in this stage. It takes account of different probable ternary phase diagrams and the idea of domain existence is transverse in this crystallization stage. Phase 3 is the final stage where crystallization of co-crystals is identified and the features are contrasted with other potential substances like free drug or salts. It provides the base for identifying the best solid structure. Figure 2) The Solvias modular co-crystal program Pharmaceutical Co-crystals Application of co-crystal ideas have come into action recently as a way of enhancing stability, IP status and solubility with reference to creating active pharmaceutical ingredients (APIs). In this context, co-crystallization does not base on the counterion and ionization for making solids. In its place, both the components make use of important intermolecular relations like hydrogen bonding to connect and give a consistent crystalline material. Combination of API together with pharmaceutically legal agent in a guest/host situation has become increasingly gorgeous course for manufacturing pharmaceutical products. For instance, co-crystallization provides an alternative during salt screening when it is either impossible or unsuccessful, due to insufficient ionization sites, to make improvement on the physical characteristics of the drug. More so, exploring of co-crystallization prospective around an API boosts the intellectual property safety over a specific drug product. In turn, it reduces the risk costly legal actions and market attrition (Vishweshwar et al. 56). A recent innovation in this field looked at crystallization as an option to salt research and the combination can give rise to co-crystals of salts. Perfect examples of this aspect are observed in laboratories and they allow stabilization of previously unstable forms of salts providing further safety of IP. At pharmaterials co-crystal screening is the forefront of all activities. The unique co-crystallisation at this place follows the extensive research done internally and it incorporates amalgamation of high- through-put grinding, sonication, evaporation and slurrying techniques. Additionally, the institution provides a wide range of solid structure analysis aiming at selecting the best developable pharmaceutical co-crystal (Vishweshwar et al. 90). Works Cited Day, A. I. et al, "A Cucurbituril-Based Gyroscane: A New Supramolecular, Australia". Angew. Chem. New York: Harper & Row, 2002. Print Graham D. and Eddie T., X-ray Techniques in Art Galleries and Museums (1985); B. H. Kevles, Naked to the Bone: Medical Imaging in the Twentieth Century, 2001. Print Khan I. "The Growth and Structure of Single-Crystal Films," in Handbook of Thin Film Technology, Leon I.Maissel and Reinhard Glang, Editors, New York: McGraw-Hill Book Company, 2005. Print. Ramenar J. et al., "Crystal Engineering of Novel Co-crystals of a Triazole Drug with 1,4-DicarboxylicAcids," Journal of the American Chemical Society, Patent reference New York: Harper & Row, 2003. Print Solvias A. Co-Crystals – An Attractive Alternative for Solid Forms, New York: Harper & Row. 2007. Print Vishweshwar P. et al., "Pharmaceutical co-crystals," Journal of Pharmaceutical Science, New York: Harper & Row, 2006. Print Read More