A symmetrical azo-based fluorophore and the derived salen multipurpose framework for emissive layers

Diana, Rosita; Panunzi, Barbara; Shikler, Rafi; Nabha, Shiran; Caruso, Ugo

doi:10.1016/j.inoche.2019.04.016

Cited by 28 publications

(30 citation statements)

References 30 publications

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“…The intramolecular hydrogen-bond interactions in the half-salen moieties cause the excited-state intramolecular proton-transfer (ESIPT) [60,61] known to lead to emission in solution [46,59,[61][62][63][64][65][66]. The same effect is known to occur in the solid state [12,67] if the intramolecular H-bond produce hindrance to the torsion of sterically encumbered parts of the molecule [57,68,69]. In our case, the acetyl substituents on the furan rings and the bulky naphthol moieties make NBDF a RIR probe.…”

Section: Resultsmentioning

confidence: 70%

“…Compound NBDF is the condensation product between a diamine and a salicylic aldehyde in 1:2 ratio. The probe contains two half-salen [12,[57][58][59] Schiff base sites working as electron-donor arms and an electron-acceptor core. As shown in Scheme 1, the (4-nitrophenyl) benzodifuran unit represents the acceptor moiety due to the strong electron-withdrawing properties of the nitro substituent.…”

Section: Resultsmentioning

confidence: 99%

“…To further explore the potential applications of NBDF probe in the production of emissive layers, the fluorophore was mixed with poly(vinylcarbazole) (PVK), a polymeric conductive matrix often employed in optoelectronic devices. Production of polymeric blends, and more generally deposition of low-weight molecules on conductive substrates [45,57,74], is a functional approach to produce macroscopically processable layers. For ACQ undergoing molecules this is a way to relieve fluorescence quenching effect [45,57].…”

Section: Production Of a Red Emissive Polymeric Layermentioning

confidence: 99%

“…Production of polymeric blends, and more generally deposition of low-weight molecules on conductive substrates [45,57,74], is a functional approach to produce macroscopically processable layers. For ACQ undergoing molecules this is a way to relieve fluorescence quenching effect [45,57]. In our case, the AIE performance of the dye required the employ of a high percentage of NBDF in the amorphous host matrix.…”

Section: Production Of a Red Emissive Polymeric Layermentioning

confidence: 99%

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A Novel DR/NIR T-Shaped AIEgen: Synthesis and X-Ray Crystal Structure Study

et al. 2020

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We developed a new benzodifuran derivative as the condensation product between 2,6-diamino -4-(4-nitrophenyl)benzo [1,2-b:4,5-b']difuran-3,7-dicarboxylate and 3-hydroxy-2-naphthaldehyde. The intramolecular hydrogen-bond interactions in the terminal half-salen moieties produce a sterically encumbered highly conjugated main plane and a D-A-D (donor-acceptor-donor) T-shaped structure. The novel AIEgen (aggregation-induced enhanced emission generator) fulfils the requirement of RIR (restriction of intramolecular rotation) molecules. DR/NIR (deep red/near infrared) emission was recorded in solution and in the solid state, with a noteworthy photoluminescence quantum yield recorded on the neat crystals which undergo some mechanochromism. The crystal structure study of the probe from data collected at a synchrotron X-ray source shows a main aromatic plane π-stacked in a columnar arrangement.Crystals 2020, 10, 269 2 of 15 law [20][21][22] the intrinsic low band-gap of such DR/NIR emitters makes them especially vulnerable to the ACQ effect [23] due to higher vibrionic coupling between the ground and excited states. Therefore, most of the AIEgens reported emit blue and green lights. Although they are highly sought after for red OLEDs (Organic Light Emitting Diodes), night-vision devices, secured displays, optical waveguides and in the wide field of bio and chemo-sensing [24][25][26][27][28], there are fewer efficient DR/NIR (deep red/near infrared) materials. Of particular interest are AIE fluorophores with intense emission at DR/NIR region owing to their deep tissue penetration, photo-stability and minimum interference in living systems [25,29,30]. Their applications are closely related to cell imaging and DNA and protein sensing [31][32][33].Novel molecular construction of DR/NIR AIEgens can be achieved with electron donor (D) and electron acceptor (A) blocks connected through π-conjugated frameworks. The most fundamental phenomenon governing the spectroscopic properties is the intramolecular charge transfer (ICT) process from the donor to the acceptor in the excited state [34][35][36]. Intercrossed excited state between the low-lying local exciton (LE) and charge transfer (CT) exciton results from the D-A interaction. Obviously, the molecular geometry is crucial for the process.Benzodifuran derivatives have drawn attention for a wide range of biological and pharmacological applications, including antimicrobial, antiviral, analgesic and antitumor [37][38][39][40] activity. This class of heterocyclic compounds are also employed in dyes industry as pigments and in different fields of optoelectronics and photonics. Due to the excellent semiconducting properties [41,42], benzodifuran scaffolds are used as nonlinear optical materials [43], for dye sensitized solar cells [44] and in organic solar cell and transistors. Finally, as electron-rich building blocks they have a potential in the constructing of photoluminescent materials [45][46][47] Herein, we developed a new benzodifuran derivative from 2,6-diamino-4-(4-nitrophenyl) ...

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Section: Resultsmentioning

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Section: Production Of a Red Emissive Polymeric Layermentioning

confidence: 99%

Section: Production Of a Red Emissive Polymeric Layermentioning

confidence: 99%

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A Novel DR/NIR T-Shaped AIEgen: Synthesis and X-Ray Crystal Structure Study

et al. 2020

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“…2-hydroxy-4-nitrobenzaldehyde was obtained as described in [56]. 4,4 -((1,1 )-(2,5-dimethoxy-1,4-phenylene)bis(diazene-2,1-diyl))dianiline (AB-NH 2 ) was obtained as described in [13]. 1 H NMR spectra were recorded in DMSO-d 6 , with a Bruker Advance II 400 MHz apparatus (Bruker Corporation, Billerica, MA, USA).…”

Section: Methodsmentioning

confidence: 99%

Spectroscopic Behaviour of Two Novel Azobenzene Fluorescent Dyes and Their Polymeric Blends

et al. 2020

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Two novel symmetrical bis-azobenzene red dyes ending with electron-withdrawing or donor groups were synthesized. Both chromophores display good solubility, excellent chemical, and thermal stability. The two dyes are fluorescent in solution and in the solid-state. The spectroscopic properties of the neat crystalline solids were compared with those of doped blends of different amorphous matrixes. Blends of non-conductive and of emissive and conductive host polymers were formed to evaluate the potential of the azo dyes as pigments and as fluorophores. Both in absorbance and emission, the doped thin layers have CIE coordinates in the spectral region from yellow to red. The fluorescence quantum yield measured for the brightest emissive blend reaches 57%, a remarkable performance for a steadily fluorescent azo dye. A DFT approach was employed to examine the frontier orbitals of the two dyes.

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