Xanthene

About: Xanthene is a research topic. Over the lifetime, 2132 publications have been published within this topic receiving 34803 citations. The topic is also known as: Xanthene & dibenzo[a,e]pyran.

Deep Red to NIR Emitting Xanthene Hybrids: Xanthene‐Hemicyanine Hybrids and Xanthene‐Coumarin Hybrids

Abstract: Xanthene dyes exhibit remarkable photophysical properties and photostability. Their ability to switch fluorescence on/off depending on the external environment makes them a promising candidate for imaging/sensing/tracking/labeling probes. However, their emission ≤600 nm and Stokes shift ∼34 nm restrict their use in biological applications. A well-known approach to shifting the emission of xanthene dyes in the deep red to Near infrared (NIR) is by forming xanthene hybrids. This review gives a comprehensive list of the deep red to NIR xanthene-hemicyanine and xanthene-coumarin hybrids. We have outlined general synthetic strategies and a detailed discussion of substituent effect, π-conjugation, and ring effect on the photophysical properties of these dyes. A section on applications of deep red to NIR xanthene hybrids based on fluorophore-linker strategy and spirocyclization is included. This review highlights the structure-spectroscopic relationships, which will be useful in designing new deep red to NIR xanthene analogs.

Ways of light stabilization of natural dyes using fullerene C60

Abstract: Среди технических функциональных продуктов в различных отраслях промышленности особое место занимают красители, количество которых в настоящее время составляет более 10 тыс. индивидуальных веществ различных классов (азокрасители, антрахиноновые, ксантеновые, тиазиновые, акридиновые и др.). Для практических целей в пищевой промышленности востребованы яркие, светостойкие и безвредные красители природного и синтетического происхождения. Имеющееся количество видов таких красителей недостаточно для удовлетворения всех потребностей различных производств. Особенно востребованы красители с повышенной светостойкостью. Поэтому в настоящее время получение новых видов светостойких красителей и разработка технологий их производства являются весьма актуальными. Представлены результаты экспериментов по подбору исходного растительного сырья для выделения природных антоциановых красителей методом водной экстракции из ягодного жмыха водой, которая предварительно настаивалась на шунгитовом щебне, содержащем фуллерен. Установлено интенсифицирующее действие шунгитовой воды на степень извлечения антоцианов методом экстракции. Предложен механизм экстракционного выделения красителей. Для светостабилизации красителей, выделенных при экстракции, проведена их адсорбция на порошковых материалах, состоящих из углеводов и белков. Полученные цветные порошки обладали высокой светостойкостью. Предложены механизм светостабилизации красителей и пути использования светостабилизированных красителей. На основании проведенного аналитического обзора определено наиболее рациональное направление выделения антоциановых красителей из доступного природного сырья в присутствии инновационного наноматериала - фуллерена, обладающего антиоксидантными и антирадикальными свойствами. С целью повышения эффективности водной экстракции проведены исследования по изучению способов предварительной подготовки исходного сырья, необходимых для увеличения степени выделения красных натуральных красителей. Разработан новый способ выделения и длительного сохранения цветности антоциановых красителей методом нанесения их на твердые формы углеводов и белков различного химического строения в присутствии фуллерена. Предложен антирадикальный механизм повышения светостойкости антоциановых и беталаиновых красителей. Among the technical functional products in various industries, a special place is occupied by dyes, the number of which currently amounts to more than 10 thousand individual substances of various classes (azo dyes, anthraquinone, xanthene, thiazine, acridine, etc.). For practical purposes in the food industry, bright, light-resistant and harmless dyes of natural and synthetic origin are in demand. The available number of types of such dyes is not enough to meet all the needs of various industries. Dyes with increased light resistance are especially in demand. Therefore, at present, the production of new types of light-resistant dyes and the development of technologies for their production are very relevant. The results of experiments on the selection of initial plant raw materials for the isolation of natural anthocyanin dyes by water extraction from berry cake with water that was previously infused on shungite crushed stone containing fullerene are presented. The intensifying effect of shungite water on the degree of anthocyanin extraction by extraction has been established. The mechanism of extraction of dyes is proposed. For light stabilization and dyes isolated during extraction, their adsorption was carried out on powdered materials consisting of carbohydrates and proteins. The resulting colored powders had high light resistance. The mechanism of light stabilization of dyes and ways of using light-stabilized dyes are proposed. Based on the conducted analytical review, the most rational direction of isolation of anthocyanin dyes from available natural raw materials in the presence of an innovative nanomaterial - fullerene, which has antioxidant and antiradical properties, has been determined. In order to increase the efficiency of water extraction, studies have been conducted to study the methods of preliminary preparation of raw materials necessary to increase the degree of isolation of red natural dyes. A new method has been developed for the isolation and long-term preservation of anthocyanin dyes by applying them to solid forms of carbohydrates and proteins of various chemical structures in the presence of fullerene. An antiradical mechanism for increasing the light resistance of anthocyanin and betalain dyes is proposed.

Xanthene dyes for electrophotographic recording procedures

Abstract: The invention relates to xanthene dyes of the formula I in which R stands for methyl, ethyl or or for pyrrolidino, piperidino or morpholino, R stands for hydrogen, methyl or ethyl, R stands for hydrogen or methyl and R stands for hydrogen or C1-C4-alkyl, where, if R is methyl or ethyl, R stands for C1-C4-alkyl. The dyes I are outstandingly suitable for the preparation of toners.

3',6'-Bis(ethyl-amino)-2',7'-dimethyl-2-{2-(E)-[(thio-phen-2-yl)methyl-idene-amino]-eth-yl}spiro-[isoindoline-1,9'-xanthen]-3-one methanol monosolvate.

Abstract: The title compound, C33H34N4O2S·CH3OH, was prepared as a spiro­lactam ring formation of rhodamine 6 G dye for comparison with a ring-opened form. The xanthene and spiro­lactam rings are approximately planar [r.m.s. deviations from planarity = 0.122 (3) and 0.072 (6) A, respectively]. The dihedral angles formed by the spiro­lactam and thio­phene rings with the xanthene ring system are 89.7 (6) and 86.5 (2)°, respectively. The crystal structure features N—H⋯O and C—H⋯O hydrogen bonds.