LiFE Assessment Tool

As part of an ongoing study to construct a molecular Turing machine in which a polymer chain is encoded via allosteric information transfer between macrocyclic complexes, we describe the thermodynamic and kinetic characterization of a multicomponent self-assembled system based on a zinc porphyrin macrocyclic compound, a bidentate ligand (1,4-diazabicyclo[2.2.2]octane, DABCO), and a viologen-substituted polymer guest. Initial addition of DABCO to the porphyrin macrocycle in chloroform solution leads to the formation of a stable 2:1 (porphyrin:DABCO) dimeric complex, even under dilute conditions, by means of strong cooperative interactions involving hydrogen and metal-ligand bonds. Further titration of the porphyrin-DABCO mixtures with the polymer gives rise to a complex array of species in the solution. The system is analyzed in detail by a combination of spectroscopic measurements and computational modeling. Each association constant in the binding scheme and the fraction of each individual complex that is formed in solution are determined precisely using a mass-balance model. Kinetic studies revealed that the rates of the polymer threading and dethreading in and out of the dimeric system are remarkably slow, indicating that the polymer is locked inside the cavity of the stable 2:1 dimeric complex as a result of strong allosteric interactions

Konduritol türevlerinin sentezlenmesinde yeni yöntemler.

Conduritols have attracted a great deal of attention in recent years owing to biological activities exhibited by them and also their usefulness in the synthesis of other natural products and pharmaceuticals. Conduritols show interesting inhibitor activity for some glycosidases and serve as important intermediates in the synthesis of inositols. In this study, novel synthetic strategies leading to highly functionalized cyclohexene derivative containing an aromatic ring, namely phenyl-substituted conduritol was achieved successfully for the first time. As the starting material, substituted benzoquinone derivative, biphenyl-2-ol was used. Bromination of one double bond followed by the reduction of the carbonyl groups served the desired skeleton. Further substitution of the bromine atoms and functionalization of the remaining double bond opened up an entry for the synthesis of substituted conduritol and inositol derivatives. Moreover, by the use of hydroquinone as a starting material we developed new synthetic methodologies for the synthesis of another conduritol derivative, bromo-substituted conduritol for the first time. Oxidation of hydroquinone to the corresponding quinone followed by the bromination of one double bond gave the desired product. After the reduction of the carbonyl groups and protection of the hydroxyl groups, the key compound for the synthesis of bromo-substituted conduritol was obtained. As a result, we enabled to synthesize new conduritol derivatives and we had considerable advance for the synthesis of other conduritol derivatives, inositols and quercitols.M.S. - Master of Scienc

Pushing the limits of chiral amplification in supramolecular polymers

N,N',N''-trialkylated-benzene-1,3,5-tricarboxamides (BTAs) self-assemble via strong, threefold αhelix type intermolecular hydrogen bonding into well-defined, helical, one dimensional columnar aggregates. The introduction of a stereogenic centre into the alkyl side chains of BTAs gives rise to strong Cotton effects in dilute apolar solutions indicating the preference for one helical conformation over the other. Here, we summarise our research on the influence of the position of the stereogenic centre on the aggregate stability and the degree of amplification of chirality in BTAs. In addition, we disclose our results on creating a preferred helical sense in BTAbased supramolecular polymers by introducing H/D isotope chirality into the alkyl side chains of BTAs at the a-position. We determine the relative stabilities of the leftand right-handed helical conformers formed by these deuterated molecules by performing a conformational analysis in different alkane solvents. Our findings show that the subtle difference between the stabilities of the two conformers leads to a cooperative self-assembly process, which is highly sensitive to the applied solvent.</p

Synthesis of bromo-conduritol-B and bromo-conduritol-C as glycosidase inhibitors

For the synthesis of bromo-conduritol-B skeleton, bromo-1,4-benzoquinone was subjected to bromination followed by the reduction of the carbonyl groups with NaBH4. Substitution of bromides bonded to sp(3)-hybridized carbon atoms with AgOAc gave the bromo-concluritol-B tetraacetate in high yield. For the construction of bromo-conduritol-C skeleton, 2,2-dimethyl-3a,7a-dihydro-1,3-benzodioxole was used as the starting material. Photooxygenation of the diene unit gave an unsaturated bicyclic endoperoxide. Bromine was incorporated into the molecule by the addition of bromine to the double bond. Opening of the peroxide linkage followed by HBr elimination and reduction of the carbonyl group provided the conduritol-C structure in good yield. Bromo-conduritol-B exhibited strong enzyme-specific inhibition against alpha-glycosidase

Synthesis of phenyl-substituted conduritol B and its mechanism of formation

The phenyl-substituted conduritol B 8 was prepared in racemic form in a five-step sequence starting from 2-phenyl-1,4-benzoquinone(10) (Scheme 1). The reaction mechanism of the key step 12b -> 13 is discussed (Scheme 2)

Benzene-1,3,5-tricarboxamide : a versatile ordering moiety for supramolecular chemistry

After their first synthesis in 1915 by Curtius, benzene-1,3,5-tricarboxamides (BTAs) have become increasingly important in a wide range of scientific disciplines. Their simple structure and wide accessibility in combination with a detailed understanding of their supramolecular self-assembly behaviour allow full utilization of this versatile, supramolecular building block in applications ranging from nanotechnology to polymer processing and biomedical applications. While the opportunities in the former cases are connected to the self-assembly of BTAs into one-dimensional, nanometer-sized rod like structures stabilised by threefold H-bonding, their multivalent nature drives applications in the biomedical field. This review summarises the different types of BTAs that appeared in the recent literature and the applications they have been evaluated in. Currently, the first commercial applications of BTAs are emerging. The adaptable nature of this multipurpose building block promises a bright future

Towards racemizable chiral organogelators

A chiral organogelator has been synthesized that can be racemized and self-assembled in apolar solvents whilst at higher concentrations organogels are formed. Field emission scanning and transmission electron microscopy revealed the formation of bundle fibrils that are able to gelate the solvent. 1H NMR studies showed hydrogen-bond interactions between the peptide head groups of neighbouring organogelator molecules. The enantiomerically pure organogelator can be racemized by the base DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) as was evident from chiral high-performance liquid chromatography analysis

Designing processive catalytic systems. Threading polymers through a flexible macrocycle ring

The translocation of polymers through pores is widely observed in nature and studying their mechanism may help understand the fundamental features of these processes. We describe here the mechanism of threading of a series of polymers through a flexible macrocyclic ring. Detailed kinetic studies show that the translocation speed is slower than the translocation speed through previously described more rigid macrocycles, most likely as a result of the wrapping of the macrocycle around the polymer chain. Temperature-dependent studies reveal that the threading rate increases on decreasing the temperature, resulting in a negative activation enthalpy of threading. The latter is related to the opening of the cavity of the macrocycle at lower temperatures, which facilitates binding. The translocation process along the polymer chain, on the other hand, is enthalpically unfavorable, which can be ascribed to the release of the tight binding of the macrocycle to the chain upon translocation. The combined kinetic and thermodynamic data are analyzed with our previously proposed consecutive-hopping model of threading. Our findings provide valuable insight into the translocation mechanism of macrocycles on polymers, which is of interest for the development of processive catalysts, i.e., catalysts that thread onto polymers and move along it while performing a catalytic action

Improvement of Filter Estimates Based on Data from Unmanned Underwater Vehicle with Machine Learning Insansiz Sualti Aracindan Alinan Verilere Baǧli Filtre Kestirimlerinin Makine Öǧrenmesi ile Iyileştirilmesi

© 2020 IEEE.In this study, the mathematical model of unmanned underwater vehicle is obtained in 6 DOF. The navigation sensor data are generated from mathematical model response. Extended Kalman filer and Unscented Kalman filter is applied to estimate noisy sensor data. For the EKF, nonlinear model is linearized around the equilibrium points. For the UKF, nonlinear system model is used. The estimation performance of EKF and UKF are compared. Estimation has been improved by applying support vector machine algorithm, which is machine learning, for unscented Kalman filter estimates. All this study is modeled in MATLAB/Simulink and PYTHON environment

Designing Processive Catalytic Systems. Threading Polymers through a Flexible Macrocycle Ring

The translocation of polymers through pores is widely observed in nature and studying their mechanism may help understand the fundamental features of these processes. We describe here the mechanism of threading of a series of polymers through a flexible macrocyclic ring. Detailed kinetic studies show that the translocation speed is slower than the translocation speed through previously described more rigid macrocycles, most likely as a result of the wrapping of the macrocycle around the polymer chain. Temperature-dependent studies reveal that the threading rate increases on decreasing the temperature, resulting in a negative activation enthalpy of threading. The latter is related to the opening of the cavity of the macrocycle at lower temperatures, which facilitates binding. The translocation process along the polymer chain, on the other hand, is enthalpically unfavorable, which can be ascribed to the release of the tight binding of the macrocycle to the chain upon translocation. The combined kinetic and thermodynamic data are analyzed with our previously proposed consecutive-hopping model of threading. Our findings provide valuable insight into the translocation mechanism of macrocycles on polymers, which is of interest for the development of processive catalysts, i.e., catalysts that thread onto polymers and move along it while performing a catalytic action