Structure-Activity Relationship Of Fluoroquinolones And Coherent Control In Rydberg Potassium Atom By Laser Pulses

There are two parts in this dissertation, in first part, we study thestructure-activity relationship between fluoroquinoiones and Gram bacteria by usingthe principal component analysis and hierarchial cluster analysis. Compared theanalytical results with the clinic experiments, accordant results are obtained. So thisinvestigation can provide a theoretical basis for designing the new fluoroquinoloneswith higher antibacterial activity, thus reducing the unnecessary use of finance,manpower, material resources. In second part, we have calculated the coherentpopulation transfer among the three quantum states of potassium atom (three-levelladder system) by a single frequency-chirped laser pulses and two-mode field byusing the time-dependent multilevel approach, respectively.Structure-activity relationship is an important means to study the drug design. Inorder to obtain the dependent rule between the biological activities and theirstructures of drugs, the structure-activity relationship is studied and elucidated, thuswe can know the action mechanism and action mode of drug and predict thebiological activities of the compounds. Multivate statistic analysis is a kind ofstatistic method having mutivariables and an important branch that is used widely inmathematics and physics. In the study of quantitative structure-activityrelationship(QSAR), principal component analysis, hierarchial cluster analysis et.al are used widely in every field. The integration of QSAR and Multivate statisticmethod can open out the structural factors and physical chemical factors ofpharmacodynamics which are affected by compounds and predict the biologicalactivities of the compounds.In first part of the paper, we have calculated the molecular properties of 18fluoroquinolones by using density function theory and divided these drugs into twoparts: one is experimental set, the other is test set. We studied the structure-activityactivities between fluoroquinolones and Gram-negative bacteria such as B.fragilis,E.coli, K. penumoniae and those between fluoroquinolones and Gram-positivebacteria such as S.pneumoniae, S.aureus, S.epidermidis. It is showed that the resultsof principal component analysis are in accord with those of hierarchial clusteranalysis. We found that the two methods all can provide a reliable rule for theclassification of new fluoroquinolones by comparing the results of test set with clinicexperiments. In addition, it is found that E_LUMO,â–³E_HL,μ, Q₂, Q₃, Q₆, Q_B,MP, MR, log P et.al. have the most important role for inhabiting the activity ofGram-negative bacteria, and Ofloxacin, Levofloxacin, Sparfloxacin, Gatifloxacin,Moxifloxacin, Grepafloxacin, Gemifloxacin and Balofloxacin have the higheractivity than the others. While E_LUMO,â–³E_HL,μ,Q₃,Q₅,MP,MR,log P et.al.have the most important role for inhabiting the activity of Gram-positive bacteria,and Grepafloxacin, Gemifloxacin, Levofloxacin, Balofloxacin, Gatifloxacin havehigher activity, while Norfloxacin, Lomefloxacin, Fleroxacin, Enoxacin have loweractivity.Comparing their structures we find the substituent of 1-nitrogen has greatcontribution to the antibacterial activity whether it is Gram-positive bacteria andGram-negative bacteria or not. When the substituent is ethyl or fluorin ethyl that hasthe similar volume with ethyl in alkyl, the antibacterial activity is the best. Moreover,the antibacterial activities of fluoroquinolones that have piperazine at 7-position arelower than that of fluoroquinolones that have piperzine which has substituent groupat 7-position. The results are agreement with thoes of clinic experiments, thusproviding the theoretical base for synthesizing new fluoroquinolones. With the development of chirped laser technology, population transfer amongquantum states controlled by chirped laser pulse and chirped microwave pulse hasbecome the important means to control the process of chemical reaction kinetics andto control the atom and molecule. It will further make people know the atomicstructure and the interaction between atom and other microcosmic particles by wideand comprehensive study. For three-level system, the best method is to transferpopulation from the initial state to the final state directly, leaving no population inthe intermediate state, in the adiabatic range. The two "intuitive"Ï€pulses canobtain the same result, but technology ofÏ€pulse needs to control pulse areaexactly and has rigorous terms for the experimental condition. While STIRAPmethod not only makes the system suffering adiabatic process but also has notrigorous terms for the pulse shape, intensity, frequency-modulated and experimentalconditions. So STIRAP method obtains the attention widely. The three-level laddersystems studied by prevenient theories and experiments are all the populationtransfer from the lower state to the higher state, while the study of three-levelsystem from the higher state to the lower state is little at present. The prevenienttheories are all under ideal condition, that is to say they only consider the threestates studied, neglecting the effect of other states. In second part of this dissertation,considering the effect of 117 states close to the system firstly, we have calculated thecoherent population transfer among the three quantum states of potassium atom(three-level ladder system) by using STIRAP method andthe time-dependentmultilevel approach. The results of STIRAP method show that population transfer isrelated to the pulse duration and overlap. The population can be directly channeledto the final state, leaving no population in the intermediate state when the pulseduration T and delayÏ„are tuned to an appropriate value. The laser frequencieseach can be tuned off their respective resonant frequency, but the combination ofPump and Stokes frequencies must be resonant with the two-photo Ramantransition.In STIRAP method, at least two laser pulses are involved in the processes ofthe coherent population transfer between the initial state and the final state. A question arises: can a single laser pulse provide coherent transfer of the atomicpopulation between the initial state and final state? In recent years, the coherenttransfer in the theories and experiments are attended by using a single laser with achirped frequency. Considering the effect of 117 states close to the system firstly, wehave calculated the coherent population transfer among the three quantum states ofpotassium atom (three-level ladder system) by using a single laser and thetime-dependent multilevel approach. It is noted that the population can be efficientlytransferred to a target state and be trapped there by using an "intuitive" sweep laserpulse, but the population will firstly be transferred to the intermediate state. Thepopulation can be directly transferred to the final state, leaving no population in theintermediate state by using a "counterintuitive" frequency sweep laser pulse. Inaddition, we have also calculated the interaction of a "broadband" frequency-chirpedlaser pulse with the three state ladder system. In the situation, two-photon resonancetransition occurs; a sequential "broadband" laser pulse identically with the first onecan again collect atomic population into the final state. Our calculations areagreement with the results of G.EDjotyan and have directive significance for theexperiment of laser controlling atom.