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1.
Samir Kumar Sarkar Meenakshi Pegu Santosh Kumar Behera Siva Krishna Narra Pakkirisamy Thilagar 《化学:亚洲杂志》2019,14(24):4588-4593
Typically, molecules with a twisted donor–acceptor (D‐A) architecture have been exploited for constructing thermally activated delayed fluorescence (TADF) materials. Herein, we report the first example of a thiophene‐based thermally activated delayed fluorescent molecule without a D‐A architecture. Compound 1 (2,5‐bis(2,2‐di(thiophen‐2‐yl)vinyl)thiophene) is conformationally flexible and shows weak fluorescence in the solution state but displays bright TADFin both condensed and solid states. Compound 1 crystallized in two different polymorphs ( 1 a and 1 b ). Interestingly, both polymorphs show distinctly different TADF features. The broad spectral features and the TADF characteristics of 1 have been explored for the time‐dependent multicolor (green, yellow and red) imaging of living cells. 相似文献
2.
Samir Kumar Sarkar Meenakshi Pegu Santosh Kumar Behera Siva Krishna Narra Pakkirisamy Thilagar 《化学:亚洲杂志》2019,14(24):4431-4431
3.
Insights into the AIEE of 1,8‐Naphthalimides (NPIs): Inverse Effects of Intermolecular Interactions in Solution and Aggregates 下载免费PDF全文
Sanjoy Mukherjee Prof. Dr. Pakkirisamy Thilagar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(26):8012-8023
Systematic structural perturbation has been used to fine‐tune and understand the luminescence properties of three new 1,8‐naphthalimides (NPIs) in solution and aggregates. The NPIs show blue emission in the solution state and their fluorescence quantum yields are dependent upon their molecular rigidity. In concentrated solutions of the NPIs, intermolecular interactions were found to quench the fluorescence due to the formation of excimers. In contrast, upon aggregation (in THF / H2O mixtures), the NPIs show aggregation‐induced emission enhancement (AIEE). The NPIs also show moderately high solid‐state emission quantum yields (ca. 10–12.7 %). The AIEE behaviour of the NPIs depends on their molecular rigidity and the nature of their intermolecular interactions. The NPIs 1 – 3 show different extents of intermolecular (π–π and C?H???O) interactions in their solid‐state crystal structures depending on their substituents. Detailed photophysical, computational and structural investigations suggest that an optimal balance of structural flexibility and intermolecular communication is necessary for achieving AIEE characteristics in these NPIs. 相似文献
4.
Sanjoy Mukherjee Prof. Dr. Pakkirisamy Thilagar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(29):9052-9062
Three new NPI–BODIPY dyads 1 – 3 (NPI=1,8‐naphthalimide, BODIPY=boron‐dipyrromethene) were synthesized, characterized, and studied. The NPI and BODIPY moieties in these dyads are electronically separated by oxoaryl bridges, and the compounds only differ structurally with respect to methyl substituents on the BODIPY fluorophore. The NPI and BODIPY moieties retain their optical features in molecular dyads 1 – 3 . Dyads 1–3 show dual emission in solution originating from the two separate fluorescent units. The variations of the dual emission in these compounds are controlled by the structural flexibilities of the systems. Dyads 1 – 3 , depending on their molecular flexibilities, show considerably different spectral shapes and dissimilar intensity ratios of the two emission bands. The dyads also show significant aggregation‐induced emission switching (AIES) on formation of nano‐aggregates in THF/H2O with changes in emission color from green to red. Whereas the flexible and aggregation‐prone compound 1 shows AIES, rigid systems with less favorable intermolecular interactions (i.e., 2 and 3 ) show aggregation‐induced quenching of emission. Correlations of the emission intensity and structural flexibility were found to be reversed in solution and aggregated states. Photophysical and structural investigations suggested that intermolecular interactions (e.g., π–π stacking) play a major role in controlling the emission of these compounds in the aggregated state. 相似文献
5.
Vethathiri Pakkirisamy Sridhar Mahadevan Surianarayanan Suthangathan Paramashivan Sivapirakasam Asit Baran Mandal 《Journal of Thermal Analysis and Calorimetry》2013,112(3):1335-1341
The objective of this article is to generate thermal decomposition data on fireworks tip mixture, a mixture used to coat the tip of fireworks, for easy ignition. This mixture has reportedly involved in triggering many accidents in fireworks industry. Different quantities of water were added to the mixture and its thermal characteristics were studied. Differential scanning calorimeter was used for screening tests and accelerating rate calorimeter was used for detailed studies in adiabatic and isothermal modes. The self-heat rate data obtained showed onset temperature for different quantity of water, at a range of 80–170 °C. The mixture with 40 % water wt/wt had onset at 80 °C in adiabatic mode. The same mixture on isoaging at 40 °C exhibited exothermic characteristics with a substantial rise in system pressure (57 bar). The heats of exothermic decomposition and Arrhenius kinetics were also computed. 相似文献
6.
Vadapalli Chandrasekhar Kandasamy Gopal Loganathan Nagarajan Palani Sasikumar Pakkirisamy Thilagar 《Journal of Chemical Sciences》2006,118(6):455-462
Phosphonate ligands, [RPO3]2-, are extremely versatile in the assembly of multi-tin and multi-copper architectures. We have used organostannoxane cores
for supporting multi-ferrocene and multi-porphyrin peripheries. The copper-metalated multi-porphyrin compound is an excellent
reagent for facile cleavage of DNA, even in the absence of a co-oxidant. Reaction oft-BuPO3H2 with Cu(C104)2. 6H2O in the presence of 2-pyridylpyrazole (2-Pypz) leads to the synthesis of a decanuclear copper (II) assembly. 相似文献
7.
Venkatasubbaiah K Pakkirisamy T Lalancette RA Jäkle F 《Dalton transactions (Cambridge, England : 2003)》2008,(33):4507-4513
A series of diboradiferrocenes with different aryl substituents was prepared through reaction of B,B-dichlorodiboradiferrocene with arylcopper and Grignard reagents. The mesityl and pentafluorophenyl derivatives, - and -, were fully characterized by multinuclear NMR, MALDI-TOF mass spectrometry and X-ray crystallography, and their electronic structure was examined by UV-visible spectroscopy and cyclic voltammetry. A comparison of the data for - and - with those of the parent compound - revealed the importance of electronic and steric effects of the substituents on the electronic structure of the compounds and ultimately the degree of electronic interaction between the two ferrocene moieties. An unusually large redox splitting of DeltaE = 703 mV was determined from the cyclic voltammogram of -. 相似文献
8.
Polyfunctional Lewis Acids: Intriguing Solid‐State Structure and Selective Detection and Discrimination of Nitroaromatic Explosives 下载免费PDF全文
Dr. Chinna Ayya Swamy P Prof. Dr. Pakkirisamy Thilagar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(24):8874-8882
Synthesis and crystal structures of three porphyrin‐based polyfunctional Lewis acids 1 – 3 are reported. Intermolecular HgCl ??? HgCl (linear and μ‐type) interactions in the solid state of the peripherally ArHgCl‐decorated compound 3 lead to a fascinating 3D supramolecular architecture. Compound 3 shows a selective fluorescence quenching response to picric acid and discriminates other nitroaromatic‐based explosives. For the first time, an electron‐deficient polyfunctional Lewis acid is shown to be useful for the selective detection and discrimination of nitroaromatic explosives. The Stern–Volmer quenching constant and detection limits of compound 3 for picric acid are the best among the reported small‐molecular receptors for nitroaromatic explosives. The electronic structure, Lewis acidity, and selective sensing characteristics of 3 are well corroborated by DFT calculations. 相似文献
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10.
Satyam Jena Jusaina Eyyathiyil Santosh Kumar Behera Maho Kitahara Yoshitane Imai Pakkirisamy Thilagar 《Chemical science》2022,13(20):5893
We report the design and synthesis of a series of room temperature phosphorescent phosphoramides TPTZPO, TPTZPS, and TPTZPSe with a donor (phenothiazine)–acceptor (P = X, X = O, S, and Se) architecture. All the compounds show structureless fluorescence with a nanosecond lifetime in dilute solutions. However, these compounds show dual fluorescence and room temperature phosphorescence (RTP) in the solid state. Both the intensity and energy of luminescence depend on the heteroatom attached to the phosphorus center. For example, compound TPTZPO with the P O unit exhibits fluorescence at a higher energy region than TPTZPS and TPTZPSe with the P S and P Se groups, respectively. Crystalline samples of TPTZPO, TPTZPS, and TPTZPSe show stronger RTP than the amorphous powder of respective compounds. Detailed steady-state, time-resolved photoluminescence and computational studies established that the 3n–π* state dominated by the phenothiazine moiety is the emissive state of these compounds. Although TPTZPS and TPTZPSe crystallized in the chiral space group, only TPTZPSe showed chiroptical properties in the solid state. The luminescence dissymmetry factor (glum) value of TPTZPS is small and below the detection limit, and a CPL spectrum could not be observed for this compound.The crystallization-induced room temperature phosphorescence and CPL of phosphoramides are reported. The nonplanar phenothiazine and the tetrahedral geometry of phosphorus curbed the non-radiative deactivation pathways, which led to improved RTP. 相似文献