Single Molecule Magnets and Single Chain Magnets Analysis

Single Molecule Magnets and Single Chain Magnets Analysis The structures and magnetic properties: molecular nanomagnets phenolic oxime complexes GUAN Shengyang Table of Contents (Jump to) 1 Introduction 1.1 Research background 1.2 Introduction to nanomagnets 1.2.1 Single molecule magnet 1.2.2 Single Chain magnet (magnetic nanowires) 1.3 Structure of phenolic oxime and complexes 2 Researches 2.1 Iron complex 2.2 Manganese complexes 2.3 Complex containing cobalt and sodium ions 2.4 Complex containing lanthanide 3 Conclusion 4 Bibliography Abstract The basic concepts needed to understand and model singlechain magnets will also be reviewed. 1 Introduction 1.1 Research background The researches on molecular nanomagnets began from 1990s, when the first single molecule magnet (SMM) [Mn12O12(O2CPh)16(H2O)4 was researched by Christougroup of University of Florida. [GS1]This mixed-valent manganese complex was found to have an abnormal high spin ground state of S=10[GS2] and highest blocking temperature (below which temperature could the nanomagnets show magnetic properties) in its family ([Mn12O12(O2CR)16(H2O)4], R = various). A large number of SMMs have been reported since then. These[GS3] kind of complexes display the classical property of magnetization hysteresis[GS4] and quantum properties of quantum tunnelling of the magnetization (QTM). These initial discoveries provide a molecular approach to nano-scale magnetism. Following investigation of single molecule magnets (SMMs) and single chain magnets (SCMs) explorers their potential applications in high-density information storage[GS5], quantum computing[GS6], magnetic refrigeration [GS7]and so on. However, to date, nanomagnets discovered have very low blocking temperature (TB). So it is very important to choose appropriate chelate ligands and corresponding metal centres to construct a proper complex with properties to improve blocking temperature (TB) for practical application. Phenolic oxime is a family of compounds with generic structure shown in Figure 1. The phenolate and oxime function groups could form intramolecular hydrogen bonding with its neighbour. These hydrogen bonding resulting in strong coordination effect on metal ions. Such property makes phenolic oxime a good extractant for copper[GS8] in mining industry. Detailed discussion of the phenolic oxime complex structure will be introduced in SECTION 1.3 . Figure 1 general structure of phenolic oxime In this review, knowledge of nanomagnets will be introduced firstly to provide an overview of this field. Then the structure and magnetic properties of compounds with phenolic oxime ligand will be introduced. New techniques applied in synthesis will also be included. It is hoped that this review could be used to assess the potential of phenolic oxime ligand in high performance nanomagnets. 1.2 Introduction to nanomagnets 1.2.1 Single molecule magnet It is helpful to describe the basic theory of SMM with an example. The first single molecule magnet (SMM) [Mn12O12(O2CCH3 )16(H2O) 4] 4H2O ·2CH3CO2H[GS9] was determined to have an S=10 ground spin state, which is contributed by the antiferromagnetic interactions between 4 MnIV ions and 8 MnIII ions[GS10]. However, not like normal size magnet, SMM shows slow magnetic relaxation below a characteristic blocking temperature. This phenomenon is explained by the exist of an energy barrier in reorientation process of magnetic moment. Sessoli et.al. confirmed there exists a relatively large zero-field splitting in this molecule by high-field EPR experiments with a CO2 far-infrared laser. This axial zero-field splitting leads to a splitting of the S=10 state into 21 levels: -10 , -9 , -8, -7, -6 , -5†¦0, 1, 2, 3†¦8, 9, 10. Each level is characterized by a spin projection quantum number ms, corresponding potential energy: †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ †¦..(1) D:axial zero-field splitting parameter. In [Mn12O12(O2CCH3 )16(H2O) 4] 4H2O ·2CH3CO2H D=-0.5cm-1 Figure 2 Figure 1. PovRay representation of the core of[Mn12O12(O2CCH3 )16(H2O) 4] 4H2O ·2CH3CO2H, showing the relative positions of the MnIV ions (shaded circles), MnIII ions (solid circles), and  µ3-O2 bridges (open circles[GS11]). Figure 3: Plot of potential energy of different spin state versus magnetization direction From Figure 3, it could be known that the splitting of potential energy levels resulting in a potential energy barrier in the process of changing the magnetic moment. For the example SMM, this barrier equals to E(ms=0)-E(ms=à ¢Ã¢â‚¬ Ã¢â‚¬Å¡Ã‚ ±10à ¢Ã¢â‚¬ Ã¢â‚¬Å¡)=100D. Due to the small value of D, this barrier could be easily crossed in room temperature. If sample SMM is magnetized at 1.5K, the magnetic relaxation time becomes too long to measure. When fitted into Arrhenius relationship: †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦(2) The magnetic anisotropy of the SMM is caused by the structure of the eight MnIII ions. Each MnIII ion with in octahedral crystal shows Jahn–Teller distortion. These distortion[GS12] together with spin-orbital interaction give rise to the easy axis type of magnetoanisotropy. To conclude, a typical SMM consists of an inner magnetic core with a surrounding shell of organic ligands. The desired SMM requires well isolated system which exhibit high spin ground state (S) with a high magnetic anisotropy of the easy-axis (Ising) type. The difficulty is: high spin ground state often requests for several nucleuses, but the magnetic orientation of each nuclei tends to obey Maximum Entropy Models. In this way, the highest magnetoanisotropy of a molecule couldn’t be achieved easily. Some researches show that replacing magnetic core with lanthanide[GS13] ions or using single nuclearity spincluster [GS14]could avoid this problem. Their approaches will be discussed in SECTION 2. 1.2.2 Single Chain magnet (magnetic nanowires) While clusters of SMM can be considered as zero dimensional material, it is possible that one dimensional materials such as nanowires exhibit slow magnetic relaxation and hysteresis effects which are not associated with three-dimensional (3D) order. At 1963, Glauber[GS15] predicted one dimension Ising model (easy axial) would show magnetization relaxation under low temperature. Due to insufficient knowledge in this area and stringent conditions required in the synthesis procedure, chemist wasn’t be able to find any evidences to support or against the prediction, until Gatteschi et al successfully synthesis [Co(hfac)2(NITPhOMe[GS16])] in 2001. Figure 4 Structure of NITPhOMe=4†²-methoxy-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide Figure 5 Drawing of unit cell of[Co(hfac)2(NITPhOMe)2]. Large dark spheres represent the metal ions. Hydrogen, fluorine, and most of the methyl carbon atoms have been omitted for clarity The structure of the SCM consists of Co(hfac)2 and radicals arranged in helices alternately( Figure 5). In this one dimensional structure, the magnetic core (octahedral cobalt(II) centres) has overall S=1/2 and shows easy axis of magnetization in the chain direction[SG17]. Detailed analysis of spectrums could be found in Caneschi’s report in 2001. To conclude, three essential conditions are need for design SCMs: 1) the ratio of the interaction and interactions is very large. 2) the material must behave as a 1D Ising ferro- or ferrimagnet. This requires the building block or the core of the chain have large ground state spin. 3) the interchain interactions should be minimized to avoid the magnetism of the material be associated with three-dimensional (3D) order. This final condition also apply for SMMs. 1.3 Structure of phenolic oxime and complexes Metal complexes with a planar, electronically delocalized structure have proven particularly attractive for development of cooperative electronic properties because of the strong molecule–molecule interactions that can arise from Ï€-stacking of the planar units 2 Researches 2.1 3d nanomagnet Many 3d nanomagnets have been synthesized and researched on since the first SMM was discovered. f hexanuclear MnIII SMMs based on the complex [MnIII6O2(sao)6(O2CH)2(EtOH)4](saoH2=salicylaldoxime[GS18])9-12 Spin Switching via Targeted Structural Distortion 2.2 Iron complex Variation of alkyl groups on the ligand fromt-octyl ton-propyl enabled electronic isolation of the complexes in the crystal structures of M(L1)2contrasting with Ï€-stacking interactions for M(L2)2(M = Ni, Cu). This was evidenced by a one-dimensional antiferromagnetic chain for Cu(L2)2but ideal paramagnetic behaviour for Cu(L1)2down to 1.8 K. 2.3 Complex containing cobalt and sodium ions 2.4 Complex containing lanthanide Although many magnetic transition metal complexes have been synthesised, the temperature required for transition metal complex to exhibit magnetization relaxation (i.e. blocking temperature) is too low. Hence lanthanide metals were introduced to the complex to increase the blocking temperature. 4 Bibliography [GS1]R. Sessoli, H.-L. Tsai, A.R. Schake, S. Wang,  J.B. Vincent, K. Folting, D. Gatteschi, G. Christou,  and D.N. Hendrickson, J. Am. Chem. Soc. 115  (1993) p. 1804. Sessoli, R.; Tsai, H.-L.; Schake, A.R.; Wang, S.; Vincent, J.B.; Folting, K.; Gatteschi, D.; Christou, G.; Hendrickson, D.N.J. Am. Chem. Soc.1993, 115, 1804-1816.  [GS2]à ¥Ã‚ Ã…’à ¤Ã‚ ¸Ã…  Ãƒ ¦-†¡ [GS3]Resonant magnetization tunnelling in the half-integer-spin single-molecule magnet [PPh4][Mn12O12(O2CEt)16(H2O)4] â€Å"Spin Tweaking† of a High-Spin Molecule: An Mn25Single-Molecule Magnet with anS=61/2 Ground State New Routes to Polymetallic Clusters: Fluoride-Based Tri-, Deca-, and Hexaicosametallic MnIIIClusters and their Magnetic Properties Molecular Cube of ReIIand MnIIThat Exhibits Single-Molecule Magnetism Syntheses, structures and single-molecule magnetic behaviors of two dicubane Mn4complexes [GS4]Macroscopic Measurement of Resonant Magnetization Tunneling in High-Spin Molecules

Kfc Markting Essay

Frame work: In Macro environment there are many factors that will effect the decision making in any organisation. To overcome and analyse these factors organisation can categories it in to PESTLE model which is considered as below. The macro-environmental or external factors of KFC can be identified by using PESTLE analysis which stands for Political, Economic, Social, Technology, Legal and Environmental. Political factors: This factor mainly deals with the government policies and procedures which is worked out through legislation and consists of all legal factors such as How stable is the political environment? Government position on market ethics Government view on culture and religion Government policy on Economy Taxation policy on tax rates and incentives These are some of the political factors that include legal issues, government implementations and define both the formal and informal rules under which the organization must be operated. Economic factor: KFC organization is affected with national and global economic factors such as Cost of labour, Interest and Inflation rates, Economic growth rates, Business cycle stage (e. g. recession, recovery) and Unemployment rates. Due to recession the income of the KFC has consistently dropped down and most of the employees were jobless and the rest employees were employed for very few hours also the organisation had to cut down their budget. Social factor: It includes the cultural and demographic aspects of the external macro environment. The potential of the employees who come from different back grounds and work together in the KFC and customer trends and aspect which the KFC has to consider as per their needs and wants of the customer such as changes in lifestyles, Level of education, Value in society, Demographics (age, sex, race etc. ,) and Change in consumer needs and wants. The U. K people are mostly dependent of the fast food centres as they find very busy with their schedules. Technological factor: This factor is the major driver of globalization which reduces the minimum efficient of production levels and some of the technological factors are recent technological developments, Rate of technology changes, Alternative way of providing services, New discoveries, Communication technology. The technology has now become the most important aspect in KFC as when the customers are mostly delighted and satisfied with service including latest technology that is available in the KFC. The latest Technological methods that are used to serve the customer faster are such as digital screens, wireless headphones for the staff, cooking utensils. Legal factor: The KFC has to maintain the rules and regulations related to the hygiene factors such as like employee proper training regarding the food and safety, personal hygiene, clean work environment and proper use of the utensils. This also deals with the legal environment in which the firms operate like the U. K has come up with the introduction of age discrimination legislation and increase in the minimum wage and greater requirement of recycles. When speaking about the hygiene it’s a very true example were KFC had to bare the high penalty because of failing in maintaining food hygiene. A Kentucky Fried Chicken restaurant at the Hernston Business Park in Bridgend has been fined a record ? 24,000 plus costs of ? 2,000 after pleading guilty at Bridgend Magistrates Court to multiple food hygiene offences – the largest penalty handed out to date for such offences in Bridgend County Borough. Bridgend County Borough Council brought two prosecutions against KFC (GB) Lt d resulting from inspections completed by the Public Protection team on 25 September 2005 and 22 May 2006. † Ref: http://www. bridgend. gov. k/web/groups/public/documents/press_release/018326. hcsp http://www. oup. com/uk/orc/bin/9780199296378/01student/additional/page_12. htm Environment factor: KFC by considering the environmental factor has proved to be quite friendly towards environment where it uses the paper material for the food and services carrying instead of plastic to help in reducing the global warming though it cost very high for the organisation to adopt paper materials such as paper plates, paper boxes for food parcel, glasses and cups etc. 3. The Swot Matrix The SWOT analysis is an extremely useful tool for understanding and decision making for all sorts of situation in KFC organisation. The SWOT is acronym for Strengths, Weakness, Opportunities, Threats. SWOT provides a good frame work for reviewing stratergy, position and direction of a company or business pr oposition. Need an essay? You can buy essay help from us today!

The Start of Personal Reflection Paper

The Start of Personal Reflection Paper The fine component of experiencing a family that's divided in how they practice religion is they are tolerant of different religions. It's always important to consider different people's ideas and opinions since there is always room for improvement. It isn't difficult to write because you simply have to express your thoughts and the way you see things. All the thought should be quite structured and clear. Simply speaking, the service exists, so should you want to use it in order to find a top essay, that's reason enough. To make sure that you will write the most suitable kind of essay, it is likewise important you know what it isn't. It may be difficult to compose a sort of essay for the very first time. So as to compose a self reflective essay, there is not any sum of research needed. If you chance to be in college, the range of essays you're expected to produce is increased. It's crucial that the service you select knows for sure they're only employing the very best essay writers. Employing a writing service is the perfect method to have a well-written essay to use as a guideline to make sure the essays you write are hitting each of the crucial points and are at the appropriate depth necessary for your academic grade. Discuss new strengths and weaknesses in regard to the experience you've gained. Personality is extremely important to the success of entrepreneur. The assertiveness is strength with what I would have the ability to sell the company idea to prospective clients. The body may also be a narrative. It may be better and faster to find online help with academic assignments of any sort from the superior group of authors. There's no particular format in the feeling that you should choose what things to write and the way to write it. A good example of my personal meditative growth has arrived from everyday living for a freshman. Allow the reader understand your experience clearly and the effect it might have in future. Express how useful is the wisdom and experience gained will be helpful in future. Now you must leave a particular image and experience. What Personal Reflection Paper Is - and What it Is Not An individual should have some fantastic writing and critical thinking abilities. Reflective essays are personal parts of the writer that they've translated into words. Your story ought to have an ending and it ought to be brilliant, and we are well conscious of it. Apart from writing in general is hard for most people, it is going to be harder if you don't understand what you have to write. Facts, Fiction and Personal Reflection Paper You must use your critical thinking to be able to recognize the issue or issue and understand h ow to produce a solution. You don't ever want to shed the major point of your essay or any body of work for this matter. The most important body is typically composed of three principal points spread over three paragraphs. Thus, after answering the aforementioned questions, be certain to write down all your answers. The Pain of Personal Reflection Paper On-line sales and marketing and advertising businesses will entail ability to cope with complexities. After you locate a service you prefer, don't neglect to look at my review of it. Marketing is extremely crucial to a small business. On-line sales marketing is information based company. A self-reflection paper differs greatly from the majority of other academic papers you're assigned. The report includes the in depth instructions about how to compose a reflective paper. The papers are lots more difficult to write. Reflection papers are a breeze to write as soon as you get the hang of it. Up in Arms About Personal Refle ction Paper? Your writing skills have a potent effect on your life. Throughout your reflection, you should earn a case for the way the experience has stimulated your private growth. Ease comfort is focused more on the surroundings and mental state of the individual. Ultimately, transcendence comfort comes every time a patient can rise above challenges that take place in care and recovery.

The Street By Anne Petry - 929 Words

Women have always been considered a minority in our society. They have always been seen as the inferior population. Throw the race card in the mix and it makes matters way worse. Anne Petry’s â€Å"The Street† took place in Harlem in the 1940s. In that time, Harlem was full of violence, poverty, and racial conflict. â€Å"The Street† is about Lutie Johnson and her struggles to achieve success for her and her son Bub. Lutie is a black woman who desires more than what she had to settle for in the past. She wants this for her and her son. Lutie is portrayed as a â€Å"classy† woman but she is very impressionable. She has goals set in her head and willing to do anything to reach those goals. Lutie embarks on this new life with Bub in a bad apartment building in Harlem where she meets very questionable characters. These characters â€Å"show a critical sensitivity to woman as spectacle, as a body to be looked at and made the object of male sexual desire and exploitation.† This whole novel is about the sexual exploitation of Lutie Johnson. Lutie is a vulnerable and beautiful woman that men want to take advantage of. She is looked at as a piece of meat that can be easily obtainable. In the novel, Petry also includes a female character, Mrs. Hedges, to show readers that not only men ridicule women but women do also. Three characters stand out from the story that objectifies Lutie and women in general. They are the super of the apartment building Lutie is living in, Jones, the lady who also lives inShow MoreRelatedNew Coke Failure3901 Words   |  16 PagesThe Failure of New Coke Wright State University MKT 3500 - 01 Marketing Research By Nicole Fore Taylor Gilliam Ashley Hatton John Petry Abstract During the 1980’s Coca-Cola was faced with a potentially company killing problem. They were losing market share quickly to their competitors. Pepsi was stealing a portion of the younger generation with their advertising campaign, and they proved that consumers liked Pepsi better with the â€Å"Pepsi Challenge.† To combat their falling market shareRead MoreIncome Taxation Solutions Manual 1 300300 Words   |  1202 PagesAlberta in the current calendar year. 4. A Manitoba corporation is controlled and managed by its British parent corporation. 5. A Canadian individual, who is a student at the University of Saskatchewan, earns income during the summer by operating a street-vending unit in Boulder, Colorado. 6. An individual has been employed in Canada by a large Canadian corporation. He accepts    a    transfer    to    manage,    on    a    permanent    basis,    the    corporation’s    operations    in    Denver, Colorado. He