The circularly polarized luminescence (CPL) switching is of significant interest for applications in security technologies and sensing devices. Small organic molecules (SOMs) show several advantages ...over metal complexes, supramolecular assemblies, and polymers. Therefore, the recent progress on the CPL switching in SOMs is here reviewed. The results are summarized based on the strategies used to tune factors that influence the emission properties, and thus, to realize CPL switching. The strategies that have been adopted include promoting the excimer formation of fluorescent units, changing the conformation of fluorophores, tuning the electronic structure of the π‐skeleton/substituent, and modulating the intramolecular charge‐transfer dynamics.
Switching! The circularly polarized luminescence (CPL) switching in small organic molecules (SOMs) is of great interest. However, the achievement of such a property is very challenging. In this minireview, the strategies that have been recently adopted are summarized.
Temperature‐dependent dual fluorescence and switchable circularly polarized luminescence (CPL) are two highly pursued but challenging properties for small organic molecules (SOMs). We herein disclose ...a triarylborane π‐system based on a 2,2′‐diamino‐6,6′‐diboryl‐1,1′‐binaphthyl scaffold that can serve as a versatile building block for achieving these two properties by simply choosing different amino groups. BNMe2‐BNaph with less bulky dimethylamino groups displays temperature‐dependent dual fluorescence, and can thus be used as a highly sensitive ratiometric fluorescence thermometer. On the other hand, BNPh2‐BNaph with bulky diphenylamino groups exhibits intense fluorescence in both solution and in the solid state. A change of solvent from nonpolar cyclohexane to highly polar MeCN not only shifts the CPL position to much longer wavelength but also inverts the CPL sign. In addition, the complexation of BNPh2‐BNaph with fluoride greatly enhances the CPL intensity.
The combination of two donor–π‐acceptor subunits in the 2,2′‐diamino‐6,6′‐diboryl‐1,1′‐binaphthyl scaffold generates a versatile building block for organic fluorophores exhibiting temperature‐dependent dual fluorescence and switchable circularly polarized luminescence.
Circularly polarized luminescence (CPL) has shown promising application potentials in 3D display, optical data storage, smart sensors/probers, CPL lasers, and light source for asymmetric ...photosynthesis. In the last decade, the CPL‐active small organic molecules (CPL‐SOMs) have attracted rapidly increasing research interest owing to the great advantages of SOMs, such as high luminescence efficiency, facile modification of chemical structure, fine emission wavelength tuning, precise relationships between structure and properties, and as well as easy fabrication. Promoted by the unique effects of boryl group, such as strong electron‐accepting ability, great steric effect, and Lewis acidity to bind with Lewis bases, we herein summarized our recent research results about the creation of CPL‐SOMs by modification of chiral scaffolds, such as 2.2paracyclophane, 5/7helicene, and binaphthyl, with boryl group. The preliminary results have well demonstrated that the chiral triarylborane‐based SOMs exhibit promising CPL properties, such as intense CPL in combination of high luminescence dissymmetry factor (|glum|) with high fluorescence efficiency, solvent‐induced sign inversion, facile emission wavelength tuning, high fluorescence efficiency in the solid, and substituent‐induced sign inversion.
This personal account summarizes our recent research results about the chiral triarylborane‐based small organic molecules that display fascinating circularly polarized luminescence (CPL) properties, such as combinaion of high ΦF with high |glum|, solvent‐induced sign inversion, facile emission wavelength tuning, intense solid state emission, and substituent‐induced sign inversion.
Ferulic acid (FA) has potential therapeutic effects in multiple diseases including cardiovascular diseases. However, the effect and molecular basis of FA in heart failure (HF) has not been thoroughly ...elucidated. Herein, we investigated the roles and mechanisms of FA in HF in isoproterenol (ISO)-induced HF rat model. Results found that FA ameliorated cardiac dysfunction, alleviated oxidative stress, reduced cell/myocardium injury-related enzyme plasma level, inhibited cardiocyte apoptosis in ISO-induced HF rat models. Moreover, FA reduced the co-localization of Keap1 and nuclear factor-E2-related factor 2 (Nrf2) in heart tissues of ISO-induced HF rats, and FA alleviated the inhibitory effects of ISO on expressions of p-Nrf2, heme oxygenase-1 (HO-1) and reduced nicotinamide adenine dinucleotide phosphate quinone dehydrogenase 1 (NQO1). Additionally, Nrf2 signaling pathway inhibitor ML385 showed adverse effects. FA weakened the effects of ML385 in ISO-induced HF rat models. Collectively, FA ameliorated HF by decreasing oxidative stress and inhibiting cardiocyte apoptosis via activating Nrf2 pathway in ISO-induced HF rats. Our data elucidated the underling molecular mechanism and provided a novel insight into the cardioprotective function of FA, thus suggested the therapeutic potential of FA in HF treatment.
The efficient synthetic route was disclosed to prepare optically active triarylborane-based 5helicenes, 7B-PhHC and 7B5N-PhHC. Their emission wavelengths are tunable by both the chemical structure ...modification and the tuning of excited state charge transfer dynamics via selection of appropriate solvents or addition of external F–, enabling the full-color circularly polarized luminescence with moderate to good quantum yields (0.07–0.51) and high luminescence dissymmetry factors (g lum > 5 × 10–3).
Temperature‐dependent dual fluorescence with the anti‐Kasha's rule is of great interest, but is a very challenging property to achieve in small organic molecules. The highly sensitive ...temperature‐dependent dual fluorescence of 2,2′‐bis(dimethylamino)‐6,6′‐bis(dimesitylboryl)‐1,1′‐binaphthyl (BNMe2‐BNaph), which essentially consists of two donor–π–acceptor (D‐π‐A) subunits, inspired the exploration of the importance of its structural features and the general utility of this molecular design. The reference compound MBNMe2‐BNaph, which lacks one electron‐accepting Mes2B, is found to show less sensitive temperature‐dependent dual fluorescence, suggesting that the structure of BNMe2‐Bnaph, consisting of two symmetrical D‐π‐A subunits, is very important for achieving highly sensitive temperature‐dependent dual fluorescence. In addition, it is found that another two 1,1′‐binaphthyls, CHONMe2‐BNaph and CNNMe2‐BNaph, which also consist of two D‐π‐A subunits with Mes2B groups replaced by CHO and CN, respectively, also show temperature‐dependent dual fluorescence, with the fluorescence changing in a similar manner to BNMe2‐BNaph, indicating the general utility of the current molecular design for temperature‐dependent dual fluorescence. Furthermore, the temperature‐dependent dual fluorescence behaviors, such as the relative intensities of the two emission bands, the separation of the two emissions bands, and the sensitivity of the fluorescence intensity ratio to temperature, are greatly influence by the electron acceptors.
Shine bright: Various 1,1′‐binaphthyl compounds, which have the characteristic composition of two donor–π–acceptor subunits with two dimethylamino groups and two electron acceptors (dimesitylboryl, formyl, and cyano) at 2,2′‐ and 6,6′‐positions, respectively, display the desirable property of temperature‐dependent dual fluorescence (see figure).
Triarylboranes have attracted significantly increasing research interest as a remarkable class of photoelectronic π-electron materials. Because of the presence of vacant p orbital on the B center, ...the boryl group is a very unique electron acceptor that exhibits not only electron-accepting ability through p−π* conjugation but also high Lewis acidity to coordinate with Lewis bases and steric bulk arising from the aryl substituent on the B center to get enough kinetic stability. Thus, the incorporation of a trivalent B element into π-conjugated systems is an efficient strategy to tune the electronic and stereo structures and thus the photoelectronic properties of π-electron systems. When an electron-donating group, such as amino, is present, triarylboranes would likely display intramolecular charge-transfer transitions. These kinds of molecules are often highly emissive. In addition, the geometry of the molecules has a great impact on the emission properties. In this Forum Article, we herein describe our recent progress on the charge-transfer emitting triarylborane π-electron systems with novel geometries, which include the lateral boryl-substituted π-system with amino groups at the terminal positions, the o,o′-substituted biaryl π-system with boryl and amino groups at the o,o′-positions, a triarylborane-based BODIPY system, and a B,N/S-bridged ladder-type π-system. We mainly put the emphasis on the molecular design concept, structure–property relationships, intriguing emission properties and great applications of the corresponding triarylborane π-systems.
We have disclosed a new type of 2.2paracyclophanes that contain a 2-(dimesitylboryl)phenyl and a N,N-disubstituted amino groups at two different phenyl rings. They show intense circularly polarized ...luminescence combining high fluorescence efficiency (ΦF) and luminescence dissymmetry factor (|g lum|), which are up to 0.93 and 1.73 × 10–2, respectively. In addition, the pseudo-meta derivatives display solvent-induced CPL sign inversion owing to the solvent-dependent excited-state dynamics.
New types of 2.2paracyclophane derivatives, g-BNMe2-Cp and m-BNMe2-Cp, in which electron-donating NMe2 and the electron-accepting BMes2 are introduced at the pseudo-gem and pseudo-meta positions, ...were designed and synthesized. The efficient through-space charge transfer enables the intense fluorescence with thermally activated delayed fluorescence characteristics. The quantum yields are up to 0.72 and 0.39 in cyclohexane. In addition, no significant fluorescence quenching was observed in the solid state with fluorescence quantum yields of powder up to 0.53 and 0.33. Moreover, the enantiomerically pure forms of g-BNMe2-Cp exhibit strong CPL signals with g lum up to 4.24 × 10–3.
The quest for fluorophores exhibiting large two‐photon absorption cross sections and high fluorescence efficiency is an important topic. Two 2,2’‐bithienyl derivatives are disclosed which contain two ...N,N‐disubstituted amino and two dimesitylboryl groups at 3,3’‐ and 5,5’‐positions, respectively. Despite the great steric effect of amino groups, the bithienyl skeleton still adopts a coplanar geometry. Herein, they are characterized by a quadrupolar structure and display good fluorescence efficiency and large two‐photon absorption cross sections up to 473 GM.
The two‐photon‐excited fluorophores exhibiting large two‐photon absorption cross sections and high fluorescence efficiency are highly pursued. Herein, two 3,3’‐diamino‐5,5’‐diboryl‐2,2’‐bithienyls are reported which are characterized by a quadrupolar structure and display good fluorescence efficiency and large two‐photon absorption cross sections reaching 473 GM.
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