Boolean and fuzzy logic gates based on the interaction of flindersine with bovine serum albumin and tryptophan

The naturally occurring photochromic compound, flindersine (FL), interplays with bovine serum albumin (BSA) and tryptophan (Trp). The intermolecular forces that establish between the couples FL/BSA and FL/Trp exert mutual effects on their photobehavior. These reciprocal effects can be exploited, in the field of molecular computing, to implement specific binary logic gates based on chemical inputs, physical outputs, and UV photons as power supply. Moreover, the smooth dependence of BSA and Trp fluorescence quantum yields on addition of FL moles (n(FL)) and temperature (T), allows us to process fuzzy logic. The synergistic action of the two inputs (n(FL) and T) allows the fuzzy AND logic gate to be implemented.     

Total synthesis of attenols A and B

A concise approach for the total synthesis of attenols A and B is described involving MacMillan’s α-aminooxylation, Evan’s asymmetric alkylation, Brown’s allylation, and spiro-ketalization as key steps. This approach has successfully demonstrated the α-aminooxylation protocol for the construction of the anti-1,3-diol unit.     

Molecular solvent effect on the acidity constant of protic ionic liquids

In this work how the microscopic properties of a molecular solvent affect the chemical environment of the protic ionic liquids (PILs) was analyzed. Using Reichardt’s dye as indicator of acidity, new acidity constant values for eight PILs (pK_a^PILs) were determined by spectrophotometric titration. Modifying the character hydrogen bonding donor of the molecular solvent it is possible to handle the PIL acid strength. Thus, we can turn basic PILs into acidic ones thereby the molecular solvent could be used as ‘additive’ for PILs, which allowed us to tune PILs design.     

Low detection limit spectrophotometry

An efficient, more sensitive and accurate spectrophotometric process is possible and can be used to obtain qualitative or quantitative results for analytes at limiting concentrations lower than usual. Transmission measurements (incident light power, P₀, or transmitted, P) are performed with a fluorescence spectrometer. One cell only is used to measure standards or unknown solutions, placed between the standard holder cuvette and the emission monochromator of the instrument. The source of the radiant power (P₀) is not the xenon lamp but the fluorescence or scattered radiation from the holder cuvette filled with an appropriate solution. The analyte concentration is found from a calibration graph, based upon Beer’s law or the approximate formula P₀−P=2.303P₀εbc, which is valid for dilute solutions. Determination of iron in a reference material, using 1,10-phenanthroline as the chromogenic reagent, was chosen as an example to demonstrate the suitability of the proposed method and clarify several important statistical questions. Also discussed is why and to what extent molecular fluorescence methods are more sensitive than molecular absorption methods.     

Molecular Processors: From Qubits to Fuzzy Logic

Single molecules or their assemblies are information processing devices. Herein it is demonstrated how it is possible to process different types of logic through molecules. As long as decoherent effects are maintained far away from a pure quantum mechanical system, quantum logic can be processed. If the collapse of superimposed or entangled wavefunctions is unavoidable, molecules can still be used to process either crisp (binary or multi‐valued) or fuzzy logic. The way for implementing fuzzy inference engines is declared and it is supported by the examples of molecular fuzzy logic systems devised so far. Fuzzy logic is drawing attention in the field of artificial intelligence, because it models human reasoning quite well. This ability may be due to some structural analogies between a fuzzy logic system and the human nervous system.     

Synthesis of novel furo-pyran derivatives via reaction between an isocyanide and alkylidene-substituted Meldrum’s acid

An unexpected four-component (3+1) reaction of an alkyl isocyanide with alkylidene-substituted Meldrum’s acid in CH₂Cl₂ at room temperature produces imino-furopyranones in good yields. The structures of the products are deduced from their IR, ¹H NMR, and ¹³C NMR spectra and by X-ray analysis. The products are structurally similar to 2H-furo[2,3-c]pyran-2-one natural products.     

Time-dependent bond-current functional theory for lattice Hamiltonians: Fundamental theorem and application to electron transport

The cornerstone of time-dependent (TD) density functional theory (DFT), the Runge-Gross theorem, proves a one-to-one correspondence between TD potentials and TD densities of continuum Hamiltonians. In all practical implementations, however, the basis set is discrete and the system is effectively described by a lattice Hamiltonian. We point out the difficulties of generalizing the Runge-Gross proof to the discrete case and thereby endorse the recently proposed TD bond-current functional theory (BCFT) as a viable alternative. TDBCFT is based on a one-to-one correspondence between TD Peierl’s phases and TD bond-currents of lattice systems. We apply the TDBCFT formalism to electronic transport through a simple interacting device weakly coupled to two biased non-interacting leads. We employ Kohn-Sham Peierl’s phases which are discontinuous functions of the density, a crucial property to describe Coulomb blockade. As shown by explicit time propagations, the discontinuity may prevent the biased system from ever reaching a steady state.     

cis-Selective synthesis of 2,5-disubstituted pyrrolidines

A concise approach to cis-2,5-disubstituted pyrrolidines is reported, which relies upon N-tert-butoxycarbonylmethyl substitution in a substrate derived from pyroglutamic acid. The method is especially noteworthy since a significant improvement in the conditions for a key Lawesson’s reaction have been established. Regioselective enolate generation and alkylation permits extension of the C-5 side chain.     

Solubility of freons in polar and non-polar liquids at 298.15 K

The cavity formation energy (CFE) is the free energy invested in rearrangement of the solvent molecules when a solute is inserted into a solvent, which is very important to the solubility studies. The CFE of liquid solvents; n-heptane, n-octane, cyclohexane, tetrachloromethane, benzene and water at 298.15 K has been determined. The solubility (in terms of Henry’s law constant), Gibb’s free energy of solution and ΔG_s^*, the thermodynamical quantities for the solvation process defined by Ben-Naim and Marcus of fluorine containing gases; freon-11, freon-12, freon-13, freon-14, freon-21, freon-c-318 and sulpherhexafluoride (SF₆) in above liquid solvents at 298.15 K also been calculated with this cavity formation energy. It yields good agreement with experimental results. The calculation shows importance of CFE in determining the solution properties.     

Chemo- and diastereoselective cyclopropanation of allylic amines and carbamates

A highly chemo- and diastereoselective protocol for the cyclopropanation of tertiary allylic amines with Shi’s carbenoid [CF₃CO₂ZnCH₂I] is described. The high levels of diastereoselectivity observed in these reactions may be attributed to chelation of the nitrogen atom to the zinc reagent, which then transfers a methylene unit to the syn-face of the olefin. Furthermore, a stereodivergent protocol for the cyclopropanation of a range of allylic carbamates has been developed, which provides access to both diastereoisomers of the corresponding cyclopropanes with very high levels of diastereoselectivity: cyclopropanation with the Wittig-Furukawa reagent [Zn(CH₂I)₂] proceeds under chelation control to give the corresponding syn-product, whilst reaction with Shi’s carbenoid proceeds under steric control to give the corresponding anti-cyclopropane, in >95:5 dr in both cases.     

Constructing the architecturally distinctive ABD-tricycle of phomactin A through an intramolecular oxa-[3+3] annulation strategy

Our efforts in constructing the ABD-ring of phomactin A through an intramolecular oxa-[3+3] annulation strategy is described. This struggle entailed finding a practical and efficient preparation of annulation precursor, and a realization of the unexpected competing regioisomeric pathway. The success entailed accessing the A-ring through Diels-Alder cycloaddition of Rawal’s diene. Furthermore, the discovery that the regioisomers from the annulation existed as atropisomers with respect to the D-ring olefin and that they could be equilibrated to the desired ABD-tricycle, allowing large quantities of tricycle to be accessed.     

Photolytic decomposition of dibenzylic sulfites

The photolytic decay of a library of para-substituted dibenzylic sulfites has been evaluated by UV radiation in a Srinivasan-Griffin-Rayonet photochemical reactor in various deuterated solvents. The decay for each dibenzylic sulfite was examined with respect to Swain and Lupton’s field constant, F. The rate of photolytic decay varies depending on the identity of the benzyl substituents. Furthermore, it has been observed that the solvent affects both the rate of sulfite photolytic decay as well as final product distribution.     

A Supramolecular Counter Circuit Based on Cyanine Dye Assembly

Molecular computation, a rapidly developing multidisciplinary research field, has attracted increasing attention. A series of combinational logic circuits at the molecular level have been constructed, however, the development of sequential logic circuits is still in its infancy due to the lack of ideal design tools. Taking advantage of unique assembly behaviors of cyanine dyes, we constructed a two-bit molecular counter circuit that can implement fundamental sequential logic functions, including number cumulating and descending. Further introducing a guanine-rich DNA strand as the cycle index, the counter can be reused several times and eventually be scaled up to count up to 16 numbers. The supramolecular circuit shows high programmability, flexibility, and reversibility, and it is prospected that the strategy would be applied in designing other advanced molecular circuits.     

The conductance and stability of fused dithia-heterocyclic compounds contacted with gold and platinum electrodes

The electronic transport properties of two kinds of fused dithia-heterocyclic compounds, 2,3,6,7-tetrahydrobenzo[1,2-b:4,5-b′]dithiophene (THBDT) and benzo[1,2-b:4,5-b]dithiophene (BDT), connected to gold and platinum electrodes are investigated using a self-consistent abinitio approach that combines the non-equilibrium Green’s function formalism with density functional theory. Our calculations show that the transmission at the Fermi level of the Au–THBDT–Au junction, where the THBDT molecule is connected to two gold electrodes through a gold adatom on each side, is 3.1 × 10⁻², in good agreement with the experimentally measured value (1.2 × 10⁻²). Replacement of the gold electrodes with platinum electrodes can improve the junction stability but cannot increase the zero-bias junction conductance. In contrast, due to the enhanced conjugation in BDT and the better molecule–electrode coupling, both the transmission and the stability of the Pt–BDT–Pt junction are improved significantly, demonstrating the close relation between the device performance and the device structure.     

Monitoring of yeast fermentation by ion mobility spectrometry measurement and data visualisation with Self-Organizing Maps

Ion mobility spectrometry (IMS) measurement combined with unsupervised neurocomputing is considered as a new potential method for on-line monitoring of fermentation and other processes producing volatile compounds that involve micro-organisms. This was demonstrated in a model system in which a strain of brewer’s yeast (Saccharomyces cerevisiae) was cultivated in a bench-top fermenter. Five phases of yeast growth could be detected from measurements of the exhaust gases from the fermenter, as indicated by the changes in ion mobility spectra analysed by computational methods.The data were first processed using the Self-Organizing Map (SOM) algorithm, the results showing that the phases of fermentation can be detected and identified. The cultivations were also shown by Sammon’s mapping to be comparable to a certain level of accuracy. Contaminated cultivation could be detected by its distinctive ion mobility spectrometry profile.     

A ninhydrin based colorimetric molecular switch for Hg and CH3COO/F

We have prepared a new ninhydrin-based colorimetric molecular switch (receptor 1) which gets ‘ON’ (blue) in the simultaneous presence of Hg²⁺ and CH₃COO⁻/F⁻ while the absence of any one among them leads the system ‘OFF’ (purple). The switching is highly specific in terms of its inputs as no other ion pairs were able to do the same. The corresponding UV-vis spectral changes involve a bathochromic shift in the charge transfer (CT) band of receptor 1 from 535 to 590 nm and get fitted to AND logic function. In the light of involvement of Hg(CH₃COO)₂ as a catalyst in a number of organic reactions, receptor 1 is quite promising.     

Saccharomyces cerevisiae catalyzed one-pot three component synthesis of 2,3-diaryl-4-thiazolidinones

Saccharomyces cerevisiae (baker’s yeast) catalyzed one-pot three component cyclocondensation of aryl aldehydes, amines, and thioglycolic acid in organic medium leading to 2,3-diaryl 4-thiazolidinones has been carried out for the first time.     

Isolation and Characterization of Actinoramides A-C, Highly Modified Peptides from a Marine Streptomyces sp

Reported herein is the isolation and structure elucidation of three highly modified peptides, actinoramides A-C (1-3), which are produced by a marine bacterium closely related to the genus Streptomyces. The planar structures of the actinoramides, which are composed of the unusual amino acids 2-amino-4-ureidobutanoic acid and 4-amino-3-hydroxy-2-methyl-5-phenylpentanoic acid, were assigned by chemical transformations and by interpretation of spectroscopic data, while the absolute configuration of these new peptides were defined by application of the advanced Marfey’s and Mosher’s methods.     

First total syntheses and absolute configuration of rugulactone and 6(R)-(4′-oxopent-2′-enyl)-5,6-dihydro-2H-pyran-2-one

The first efficient total syntheses of rugulactone and 6(R)-(4′-oxopent-2′-enyl)-5,6-dihydro-2H-pyran-2-one have been achieved in six steps with 51% and 48% overall yield, respectively. The key steps are Jacobsen’s hydrolytic kinetic resolution (HKR), Horner-Wadsworth-Emmons (HWE) homologation, and ring-closing metathesis reaction.