Absorption Bands In UV Spectra Research Articles

Imidazo[1,2‐a]pyridine Based D‐π‐A Fluorescent Sensor for Detection of Diethylcyanophosphonate

AbstractHerein, two fluorescent probes IM‐MN and IM‐ECA based on D‐π‐A system were synthesized, characterized, and evaluated for their photophysical properties. The probes were found to exhibit solvatochromic properties showing the range of fluorescence color in different polar solvents. The solvatochromism of the probes was further employed for DCNP detection. Both the probes showed excellent sensitivity and selectivity towards DCNP with fluorescence quenching response in the presence of DCNP, under UV lamp (365 nm). The probe IM‐ECA was found more sensitive in comparison to IM‐MN for detecting the presence of DCNP even at the nanomolar range. The SEM analysis has revealed the phenomenon of aggregation upon interaction of probe with DCNP that led to fluorescence quenching further, blue shift of the absorption band in UV spectra indicated formation of H‐ aggregates. Also, probes IM‐MN and IM‐ECA were fabricated into portable paper strips for real‐time detection that also resembles the response obtained in the solution phase.

Solvatochromism and preferential solvation of para-derivatives of guaiacol in water-N,N-dimethylformamide mixtures

The influence of the composition of the water-N,N-dimethylformamide mixed solvent on the position of the B absorption band in UV spectra of 2-methoxyphenol, its para-substituted derivatives, and corresponding phenolate anions simulating base units of natural lignin is investigated. The data obtained are interpreted in terms of the model of preferential solvation. The preferential solvation parameters and compositions of the solvation shells are calculated.

Synthesis and Properties of Titania Nanotube Doped with Small Amount of Cations

We have investigated a synthesis of metal (Nb, V, Cr, Mn, Co) -doped titania nanotubes using a solution chemical processing in order to control optical and electrical properties. Titania nanotubes doped with a small amount of cations up to 1 wt% exhibited similar morphology and XRD pattern as the pure titania nanotubes, however, color of nanotubes was changed depending on the dopants. It was found that Cr, Mn and Co doped titania nanotubes formed new absorption bands in UV spectra. On the other hand, electrical resistivity of doped titania nanotubes was lower than that of pure titania nanotubes.

Computerized resolution of overlapping bands in UV spectra using gaussian profile apporximations

A method is presented which allows the resolution of overlapping absorption bands in UV spectra, and the calculation of the peak parameters. An ICL Fortran program was used to perform this analysis, after correcting the absorption data for the presence of turbidity in the sample: the subjectivity normally associated with peak resolution procedures has been reduced to a minimum. Examples of its use are included. The theoretical basis of the method is of general applicability to any data which may be considered as the sum of a number of Gaussian distribution functions.

The kinetics of the triethylenediamine-catalysed aminolysis of phenyl N-phenylcarbamates with aniline in dioxan

The rates of aminolysis of p-substituted phenyl N-phenylcarbamates with aniline in dioxan forming N,N′-diphenylurea and corresponding phenols were followed by UV spectrophotometry. The rates of the reaction of phenyl, p-tolyl and p-methoxyphenyl N-phenylcarbamates having an electron-releasing group satisfied the equation: v = k[TED][ester]. Here, triethylenediamine used as catalyst is abbreviated as TED. Introduction of an electron-releasing group into the ester retarded the reaction with Hammett's ϱ value of +1.63. On the other hand, the elctron-attracting groups in the esters accelerated the reactions which satisfy the third-order kinetics. For example, the rate of the reaction of p-chlorophenyl N-phenylcarbamate with aniline was illustrated by the following equation. v′ = k 3[TED][ester][aniline] p-Nitrophenyl N-phenylcarbamate reacted with aniline in the presence or even in the absence of catalyst, v″ = k 2 + k 3[TED][ester][aniline] The above described reactions were catalysed only by tertiary amine. Moreover, the conductive substances and the new absorption bands in UV spectra were obtained only on the reaction of esters and TED. A probable mechanism which involves an ion pair of quaternary ammonium salt as a quasi-stable incipient intermediate, followed by a rapid attack on aniline, has been discussed.