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Naphthalonitriles featuring efficient emission in solution and in the solid state
Beilstein Journal of Organic Chemistry ( IF 2.7 ) Pub Date : 2020-12-02 , DOI: 10.3762/bjoc.16.246
Sidharth Thulaseedharan Nair Sailaja , Iván Maisuls , Jutta Kösters , Alexander Hepp , Andreas Faust , Jens Voskuhl , Cristian A Strassert

In this work, a series of γ-substituted diphenylnaphthalonitriles were synthesized and characterized. They show efficient emission in solution and in the aggregated state and their environment responsiveness is based on having variable substituents at the para-position of the two phenyl moieties. The excited state properties were fully investigated in tetrahydrofuran (THF) solutions and in THF/H2O mixtures. The size of the aggregates in aqueous media were measured by dynamic light scattering (DLS). The steady-state and time-resolved photoluminescence spectroscopy studies revealed that all the molecules show intense fluorescence both in solution and in the aggregated state. In THF solutions, a blue emission was observed for the unsubstituted (H), methyl- (Me) and tert-butyl- (t-Bu) substituted γ-diphenylnaphthalonitriles, which can be attributed to a weak π-donor capability of these groups. On the other hand, the methoxy- (OMe), methylsulfanyl- (SMe) and dimethylamino- (NMe2) substituted compounds exhibit a progressive red-shift in emission compared to H, Me and t-Bu due to a growing π-electron donating capability. Interestingly, upon aggregation in water-containing media, H, Me and t-Bu show a slight red-shift of the emission and a blue-shift is observed for OMe, SMe and NMe2. The crystal structure of Me allowed a detailed discussion of the structure–property relationship. Clearly, N-containing substituents such as NMe2 possess more electron-donating ability than the S-based moieties such as SMe. Moreover, it was found that NMe2 showed higher luminescence quantum yields (ΦF) in comparison to SMe, indicating that N-substituted groups could enhance the fluorescence intensity. Therefore, the π-donor nature of the substituents on the phenyl ring constitutes the main parameter that influences the photophysical properties, such as excited state lifetimes and photoluminescence quantum yields. Hence, a series of highly luminescent materials from deep blue to red emission depending on substitution and environment is reported with potential applications in sensing, bioimaging and optoelectronics.

中文翻译:

萘腈具有在溶液中和固态时能有效释放的特点

在这项工作中,合成并表征了一系列的γ-取代的二苯基萘腈。它们显示出在溶液中和在聚集状态下的有效发射,并且它们的环境响应性基于在两个苯基部分的位具有可变的取代基。在四氢呋喃(THF)溶液和THF / H 2 O混合物中充分研究了激发态性质。通过动态光散射(DLS)测量水性介质中聚集体的大小。稳态和时间分辨的光致发光光谱研究表明,所有分子在溶液和聚集态均显示强荧光。在THF溶液中,未取代的(H),甲基-(Me)和叔丁基观察到蓝色发射-丁基-(t -Bu )取代的γ-二苯基萘腈,可归因于这些基团的π供体能力较弱。另一方面,由于π电子的增长,与H,Me和t- Bu相比,甲氧基-(OMe),甲基硫烷基- (SMe)和二甲基氨基-(NMe 2)取代的化合物在发射方面表现出逐渐的红移。捐赠能力。有趣的是,在含水介质中聚集时,H,Me和t- Bu的发光显示出轻微的红移,而OMe,SMe和NMe 2则观察到蓝移。Me的晶体结构允许对结构-性质关系进行详细讨论。显然,含N的取代基如NMe 2具有比SMe等基于S的部分更高的供电子能力。此外,人们发现,NME 2显示出较高的发光量子产率(Φ ˚F)相比,SME,这表明N-取代的基团可以提高荧光强度。因此,苯环上取代基的π供体性质是影响光物理性质的主要参数,例如激发态寿命和光致发光量子产率。因此,据报道,取决于取代和环境,从深蓝色到红色发射的一系列高发光材料在传感,生物成像和光电方面具有潜在的应用。
更新日期:2020-12-02
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