Browsing by Author "Miladinova P."
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Item Photo stabilizers for polymers - new trends(2015-01-01) Miladinova P.; Konstantinova T.This paper is a review presenting some new trends for photostabilization of polymers by application of polymerizable stabilizers, so that chemically or ``self-stabilized`` polymers can be obtained. The derivatives of 2-(2-hydroxyphenyl)-2Hbenzotriazole (HBT) and 2,2,6,6-tetramethylpiperidine (HALS) are among the most effective stabilizers used, so their polymerizable derivatives have been the objects of many investigations. The combination of different types and chemical structures of stabilizers, acting according to different mechanisms, is a very promising method to obtain a new type of stabilizer. The influence of these compounds on the photostability of copolymers with some vinyl monomers was demonstrated. New approaches for ``one-step`` coloration and stabilization of polymers by a combination ``in-one molecule`` of a chromophore and a stabilizer were described. Two of the possibilities are presented - when the stabilizer and the chromophore are combined in-one molecule through an s-triazine ring and - when the stabilizer's fragment is connected directly to the chromophore.Item Sensor activity and logic behaviour of some 2-aminoterephthalic derivatives(2014-01-01) Miladinova P.; Georgiev N.Herein we report on the sensor activity of three blue-emitting triazine derivatives of 2-aminoterephthalic acid. The novelfompounds are conigured as a ``luorophore-receptor`` system. The luorophores designed can act as a pH-probe via an ``off-on-off`` luorescence sensing mechanism due to an internal charge transfer. The sensor activity towards cations and anions in water/DMF (1:1, v/v) media is studied by monitoring the luorescence intensity changes. The ions tested exert a high quenching effect suggesting that the compounds are sensitive to strong acid (pH<3) and strong alkaline media (pH>8). The logic function XNOR can be performed using an acid and a base as chemical inputs, while a digital comparator can be designed on the ground of pH induced changes in the spectral properties of the novel molecule.Item Synthesis and energy transfer properties of fluorescence sensing bifluorophore based on 2-aminodimethylterephthalate and 3-aminobenzanthrone(2018-01-01) Miladinova P.New bifluorophore based on 2-aminodimethylterephthalate as a donor and 3-aminobenzanthrone as an acceptor of excitation energy was synthesized and characterized. The s-triazinyl ring as the spacer between two parts was used. A new monofluorophore 2-aminodimethylterephthalate derivative was synthesized as a reference compound and investigated as well. Absorption, emission spectra and fluorescence quantum yields of synthesized compounds were measured. Due to the efficient donor-acceptor energy transfer (89 %) the acceptor fluorescence of the system, excited in the maximal absorption of the donor fluorophore, was enhanced more than 5 times with respect to the fluorescence intensity of the reference 3-aminobenzanthrone. The sensor activity of mono and bifluorophore toward protons as cations and hydroxide as anions in DMF/water was studied by monitoring the changes of the fluorescence intensity. Due to internal charge transfer (ICT) at monofluorophore and the energy transfer (ET) at bifluorophore, the designed compounds were able to act as a pH-probe via an off-on fluorescence sensing mechanism.Item Synthesis and investigation of some acid azo dyes for wool(2015-01-01) Miladinova P.; Vaseva R.; Lukanova V.The present paper describes the synthesis of one mono and two bisazo dyes with yellow, orange and red colour, which can be used as dyes for wool. They were obtained by the diazotization of a monoazo component of the mono-azobenzene type, followed by coupling with I-acid and H-acid. The monoazo components were obtained by the diazotization of sulphanilic acid and coupling with p-toluidine. All synthesized dyes were later analyzed by chromatography, IR and UV-Vis spectrometry. The dyeing performance of all dyes was evaluated on wool fabrics and their fastness properties were studied.Item Synthesis and photophysical properties of a novel terephthalic pH sensor based on internal charge transfer(2016-01-01) Miladinova P.A novel fluorescence sensing derivative of 2-aminodimethylterephthalate configured as a ``fluorophore-receptor`` system was synthesized and investigated. Due to the internal charge transfer, the designed fluorophore was able to act as a pH-probe via an ``off-on`` fluorescence sensing mechanism. The sensor activity toward protons as cations and hydroxide as anions in DMF was studied by monitoring the changes of the fluorescence intensity.Item Synthesis of a new benzanthrone probe for Ph determination based on PET and ICT(2016-01-01) Miladinova P.The synthesis and sensor activity of a novel benzanthrone fluorophore is reported. The system is configured on the ``fluorophore-receptor1-spacer-receptor2`` model able to act as a pH-probe via PET and ICT fluorescence sensing mechanism. The novel probe shows ``off-on-off`` switching properties under the transition from alkaline to acid media.