137790-57-9Relevant academic research and scientific papers
Directed polymorphism and mechanofluorochromism of conjugated materials through weak non-covalent control
Sharber, Seth A.,Mann, Arielle,Shih, Kuo-Chih,Mullin, William J.,Nieh, Mu-Ping,Thomas, Samuel W.
, p. 8316 - 8324 (2019)
Understanding and manipulating crystal polymorphism can provide novel strategies for materials discovery in organic optoelectronics. In this paper, a series of seven ester-terminated three-ring phenylene ethynylenes (PEs) exhibit structure-dependent polymorphism wherein alkyl chain length modulates the propensity to form violet or green fluorescent solid phases, as well as tunable thermal and mechanofluorochromic (MFC) transitions. These compounds harness "soft" non-covalent control to achieve polymorphism: the electronic substituent effect of the ester groups weakens the fluoroarene-arene (ArF-ArH) interactions that typically direct crystal packing of this class of compounds, increasing competitiveness of other interactions. Small structural modifications tip this balance and shift the prevalence of violet- or green-emitting polymorphs. Compounds with short alkyl chain lengths show both violet and various green fluorescent polymorphs, while the violet fluorescent form dominates with alkyl lengths longer than butyl. Further, thermally induced green-to-violet fluorescent crystal-to-crystal transitions occur for single crystals of two derivatives. Finally, the PEs show reversible violet-to-green mechanofluorochromism (MFC), with temperature required for reversion of this MFC decreasing with alkyl chain length. We therefore present this design of directional but weak interactions as a strategy to access polymorphs and tunable stimuli-responsive behavior in solids.
Smectic liquid crystals comprising triazole banana shaped achiral molecules: Synthesis and characterization
Li, Xiaolian,Zhang, Zongying,Liuya
, p. 395 - 404 (2017/05/26)
A series of novel liquid crystals containing [1,2,3]-triazole ring were synthesized via “click chemistry.” Their mesomorphic properties and photoelectric properties were investigated and the results indicated that most of compounds exhibited SmA over a wide temperature range (about 50°C). The threshold voltage and the response time of the mixture, T4 and LC 50100 were shorten 0.43?V and 71.5?ms with respect to those of LC 50100 respectively.
Fe-Catalyzed Aerobic Oxidative C-CN Bond Cleavage of Arylacetonitriles Leading to Various Esters
Kong, Weiguang,Li, Bingnan,Xu, Xuezhao,Song, Qiuling
, p. 8436 - 8443 (2016/09/28)
Fe-catalyzed aerobic oxidative esterifications of arylacetonitriles with alcohols, tri alkoxsilanes, silicate esters, or borate esters have been developed. The acyl groups which were in situ generated via chemoselective C(CO)-CN bond cleavage were directly used as electrophiles, leading to corresponding aryl esters in good to excellent yields under molecular oxygen when attacked by alcohols or alcohol surrogates. Dioxygen serves as both oxidant and reactant in this protocol. The reaction has a very broad substrate scope. Cheap starting materials as well as environmentally benign and inexpensive iron catalyst and ideal oxidant O2 feature this transformation and make it a practical and sustainable protocol to afford esters.
UV-induced fluorescence recovery and solubility modulation of photocaged conjugated oligomers
Pawle, Robert H.,Eastman, Victoria,Thomas, Samuel W.
, p. 14041 - 14047 (2012/06/01)
This article describes photoactivatable conjugated oligomers that show both increased fluorescence quantum yield and pH-dependant solubility upon irradiation with UV light. Sonogashira coupling between ester-substituted phenylacetylenes and alkoxy-substituted diiodo phenylene-vinylenes yielded conjugated phenylene-ethynylene/phenylene-vinylene oligomers. Oligomers with nitrobenzyl ester moieties had quenched fluorescence in polar solvents; UV irradiation restored their quantum yield of fluorescence to that of corresponding alkyl ester-substituted oligomers. These photocaged oligomers also exhibited UV-induced changes in solubility consistent with photogeneration of carboxylic acids. This approach is therefore effective at tuning the properties of conjugated organics with light after traditional synthetic operations, and has potential for use in photoactivatable fluorophores or solution-processable multilayer devices.
