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Covalent organic frameworks (COFs) offer remarkable versatility, combining ordered structures, high porosity, and tailorable functionalities in nanoscale reaction spaces. Herein, we report the synthesis of a series of isostructural, photoactive Wurster‐type COFs achieved by manipulating the chemical and electronic nature of the Wurster aromatic amine building blocks. A series of donor‐acceptor‐donor (D‐A‐D) Wurster building block molecules was synthesized by incorporating heteroaromatic acceptors with varying strengths between triphenylamine donor groups. These tailored building blocks were integrated into a 2D COF scaffold, resulting in highly crystalline structures and similar morphologies across all COFs. Remarkably, this structural uniformity was also achieved in the synthesis of homogeneous and oriented thin films. Steady‐state photoluminescence revealed a tunable red‐shift in film emission exceeding 100 nm, demonstrating effective manipulation of their optical properties. Furthermore, photoelectrochemical (PEC) water splitting studies exhibited a doubled current density (8.1 μA cm−2 at 0.2 VRHE) for the COF with the strongest acceptor unit. These findings highlight the potential of Wurster D‐A‐D COFs in photoelectrochemical water splitting devices and pave the way for further exploration of chemical functionality‐reactivity‐property relationships in this promising class of photoactive materials. [ABSTRACT FROM AUTHOR]

In this study, we report the design and synthesis of two novel carbazole‐based bis‐cyanostilbenes incorporating phenyl and thiophene π‐spacer units to investigate their distinct impacts on photophysical properties. Notably, the thiophene‐based derivative exhibits remarkable far‐red/near‐infrared (NIR) solid‐state emission, with an emission peak at 732 nm, which shifts to 750 nm upon mechanical grinding, demonstrating pronounced mechanochromic fluorescence in the NIR region. Although its quantum yield is moderate, the ability to modulate its emission through mechanical stimuli opens exciting opportunities for stimuli‐responsive NIR applications. Conversely, the phenyl‐based analogue shows excellent solid‐state emission at 596 nm, achieving significantly higher quantum yields, due to suppressing π‐π interactions. Both compounds also exhibit strong AIE, with the thiophene system emitting at 730 nm and the phenyl‐based analogue at 580 nm in the aggregate state. In addition to their optical properties, both derivatives demonstrate remarkable thermal stability and reversible MFC. These intriguing behaviors highlight the critical role of π‐spacer engineering in fine‐tuning solid‐state emission, enhancing stimuli‐responsive capabilities, and ensuring robust thermal performance. Overall, our findings provide valuable insights into the design of next‐generation NIR‐emissive materials, with promising potential for advancing applications in optoelectronics, bioimaging, and smart sensing technologies. [ABSTRACT FROM AUTHOR]

A series of donor‐acceptor (D−A) terpyridine derivatives with various intramolecular charge transfer interactions have been successfully synthesized bearing phenyl, methoxyphenyl, N‐butyldiphenylamine (DPA), and triphenylamine (TPA) as electron‐donors and terpyridine (TPY), 2,6‐di(pyrazin‐2‐yl)pyridine (PYDPZ), and N,N‐dimethylated PYDPZ (PYDPZ‐2CH3) as electron acceptors. Upon the introduction of pyrazine rings instead of pyridine ones and further selective N,N’‐dimethylation, the intramolecular D−A interactions are significantly enhanced, resulting in the remarkable reduced intramolecular charge transfer (ICT) transitions and quenched PL emissions in CH2Cl2 solution. However, their ICT emissions are clearly recovered upon adding Zn2+. Especially, for double positively charged compound 12, the Zn2+‐induced “turn‐on” green emission (λmax, em=518 nm, Φ=0.24) with excellent sensitivity (I/I0=77) and selectivity (IZn/ICd=23) is detected. Under the optimized experimental condition (EtOH‐H2O (9 : 1, v/v), containing 0.05 M HEPES buffer (pH=7.4)), this probe is used to quantitative determination of Zn2+ in a water sample with an average recovery of 97.5 %. Furthermore, the probe is applied to imaging of Zn2+ ions in HeLa cells and its mechanism is confirmed by the molecular dynamics simulation, in which lower coulomb potential for membrane surface adsorption and energy barrier for membrane translocation can be found. [ABSTRACT FROM AUTHOR]

We report herein a series of macrocycles in which the densely π‐stacked charge‐transfer (CT) donor/acceptor with naphthalenediimides (NDIs) or perylene diimide (PDI) as acceptor moiety pairing various donor moieties are locked by covalent bond. The X‐ray crystallography of C8BDT‐NDI reveals a short intramolecular π‐stacking distance around 3.4 Å and the existence of intermolecular donor/acceptor π‐stacking (3.7 Å). The intramolecular CT is highly dependent on the electron‐donating ability of donor moiety and replacing carbazole (C8KZ) with benzo[1,2‐b:4,5‐b′]dithiophene (C8BDT) or dihydroindolo[3,2‐b]indole (C8DN) redshift CT absorption into NIR region. Notably, both C8BDT‐NDI and C8DN‐NDI demonstrate excellent photothermal performance, which is a result of the active non‐radiative pathways. Interestingly, the different molecular symmetry between donor and acceptor moiety in cyclophanes endow C8BDT‐NDI and C8DN‐NDI with intrinsic planar chirality. The enantiomeric C8BDT‐NDI shows chiral selectivity for incident light, i.e., when irradiated by left‐circularly polarized light, (R)‐C8BDT‐NDI is more sensitive and a higher maximum stable temperature is achieved. While, enantiomeric C8DN‐NDI pack with different orientations forming M‐ and P‐handedness helix, respectively, demonstrating molecular planar chirality being transferred and amplified through molecular assembly. These results provide insight into the intramolecular charge transfer in enforced D/A π‐stacks in which CT interactions and planar chirality would be engineered through structural control. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Side‐chain engineering has emerged as a highly effective strategy for tailoring the aggregation behavior and charge transport properties of non‐fullerene small molecule acceptors (SMAs). In this study, we designed and synthesized two SMAs, namely BTPSi‐Bu and BTPSi‐Pr, respectively incorporating tributylsilyloxy and triisopropylsilyloxy groups in their outer positions. Notably, BTPSi‐Bu exhibited better planarity, crystallization, and favorable phase separation when paired with PM6 donor polymer compared to its counterpart, BTPSi‐Pr. The resulting organic solar cells, utilizing the PM6:BTPSi‐Bu blend, demonstrated a remarkable power conversion efficiency of 17.41% and a high open‐circuit voltage of 0.859 V. These findings underscore the significance of integrating trialkylsilyloxy side chains into SMAs as a rational design approach for enhancing the performance of photovoltaic systems. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Side‐chain engineering has emerged as a highly effective strategy for tailoring the aggregation behavior and charge transport properties of non‐fullerene small molecule acceptors (SMAs). In this study, we designed and synthesized two SMAs, namely BTPSi‐Bu and BTPSi‐Pr, respectively incorporating tributylsilyloxy and triisopropylsilyloxy groups in their outer positions. Notably, BTPSi‐Bu exhibited better planarity, crystallization, and favorable phase separation when paired with PM6 donor polymer compared to its counterpart, BTPSi‐Pr. The resulting organic solar cells, utilizing the PM6:BTPSi‐Bu blend, demonstrated a remarkable power conversion efficiency of 17.41% and a high open‐circuit voltage of 0.859 V. These findings underscore the significance of integrating trialkylsilyloxy side chains into SMAs as a rational design approach for enhancing the performance of photovoltaic systems. [ABSTRACT FROM AUTHOR]

Pyrene derivatives bearing substituents at positions 1, 3, 6, and 8 find numerous applications, as exemplified by their use in lasers, sensors, and bioimaging probes. However, these derivatives typically have point‐symmetric or short‐axially symmetric structures, whereas long‐axially symmetric derivatives remain underexplored because of the difficulty in obtaining their precursor, 1,3‐dibromopyrene. To address this problem, we herein synthesized 1,3‐dibromopyrene from 1‐methoxypyrene in an overall yield (71 % over four steps) considerably exceeding those of existing methods. 1,3‐Dibromopyrene was converted into 13OPA, a long‐axially symmetric pyrene dye with electron‐donor (alkoxy) groups at positions 1 and 3 and electron‐acceptor (formyl) groups at positions 6 and 8. 13OPA exhibited photophysical properties distinct from those of its point‐symmetric and short‐axially symmetric isomers, featuring a broad and strongly redshifted absorption, strong fluorescence with reduced sensitivity to protic solvents, and small dipole moment change upon photoexcitation. The derivatization of 13OPA into a Schiff base and its functionalization via Lewis acid‐base pairing were also demonstrated. Thus, our work expands the design scope of pyrene‐based molecules, particularly those used as emitters. [ABSTRACT FROM AUTHOR]

This article discusses the electrocatalytic synthesis of 1,2-dioxolanes from tetrasubstituted donor-acceptor cyclopropanes. The use of electrochemical activation allows for an alternative cleavage mode of C(sp3)-C(sp3) bonds, resulting in the formation of 1,2-dioxolanes. The study explores the optimization and reaction scope of this system, demonstrating the synthesis of 3,3,5,5-tetrasubstituted dioxolanes from various cyclopropanes. The proposed mechanism for this reaction is supported by previous studies on the electrochemical activation of donor-acceptor cyclopropanes. [Extracted from the article]

Strongly polarized donor‐acceptor‐donor′ diketopyrrolopyrroles, differing in the type of key donor moiety, were designed and synthesized to examine how this affects the non‐radiative decay. Dyes possessing less electron‐rich N‐carbazolyl substituents are characterized by strong yellow emission from a locally excited (LE) state, whereas replacing this donor with more electron‐rich N‐phenothiazinyl substituent changes the relative position of charge‐transfer (CT) and LE states, leading to weaker, reddish‐orange fluorescence. As a result, there is solvent‐dependent charge‐transfer emission shifted to as far as 700 nm. The opening of the intersystem crossing channel to the triplet state possessing CT character is the most likely cause of the fluorescence quantum yield variation in some cases. These results reveal that the fate of molecules in their excited state can be fine‐tuned by very small structural changes. [ABSTRACT FROM AUTHOR]

Luminescence in the second near‐infrared (NIR‐II, 1,000–1,700 nm) window is beneficial especially for deep tissue imaging and optical sensors because of intrinsic high permeability through various media. Strong electron‐acceptors with low‐lying lowest unoccupied molecular orbital (LUMO) energy levels are a crucial unit for donor–acceptor (D–A) π‐conjugated polymers (CPs) with the NIR‐II emission property, however, limited kinds of molecular skeletons are still available. Herein, D–A CPs involving fluorinated boron‐fused azobenzene complexes (BAz) with enhanced electron‐accepting properties are reported. Combination of fluorination at the azobenzene ligand and trifluoromethylation at the boron can effectively lower the LUMO energy level down to −4.42 eV, which is much lower than those of conventional strong electron‐acceptors. The synthesized series of CPs showed excellent absorption/fluorescence property in solution over a wide NIR range including NIR‐II. Furthermore, owing to the inherent solid‐state emissive property of the BAz skeleton, obvious NIR‐II fluorescence from the film (up to λFL=1213 nm) and the nanoparticle in water (λFL=1036 nm, brightness=up to 29 cm−1 M−1) were observed, proposing that our materials are applicable for developing next‐generation of NIR‐II luminescent materials. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Perovskite solar cells (PSCs) have been proven to be a promising option for photovoltaic conversion. With the aim to achieve efficient and stable PSCs, it is essential to explore dopant‐free hole‐transporting materials (HTMs) with high hole mobility. Herein, HTMs bearing electron donor (D)‐electron acceptor (A)‐electron donor (D) structures have been constructed with strong intramolecular charge transfer (ICT) effect, based on rational combination of dibenzo[a,c]phenazine and pyridine as electronic acceptors and anchoring groups to perovskite layer. Accordingly, high hole mobility (7.31 × 10–5 cm2·V–1·s–1) and photoelectric conversion efficiency (20.45%) have been achieved by dopant‐free DPyP‐based PSC. It afforded an efficient way to design HTMs with high hole mobility by adjustment of molecular configurations and electronic property of conjugated systems. [ABSTRACT FROM AUTHOR]

NBN‐ and BNB‐doped phenalenyls are isoelectronic to phenalenyl anions and cations, respectively. They represent a pair of complementary molecules that have essentially identical structures but opposite properties as electron donors and acceptors. The NBN‐phenalenyls 1–4 considered here were prepared from N,N'‐dimethyl‐1,8‐diaminonaphthalene and readily available boron‐containing building blocks (i. e. BH3⋅SMe2 (1), p‐CF3‐C6H4B(OH)2 (2), C6H5B(OH)2 (3), or MesBCl2/iPr2NEt (4)). Treatment of 1 with 4‐Me2N‐2,6‐Me2‐C6H2Li gave the corresponding NBN derivative 5. The BNB‐phenalenyl 6 was synthesized from 1,8‐naphthalenediyl‐bridged diborane(6), PhNH2, and MesMgBr. A computational study reveals that the photoemission of 1, 4, and 5 originates from locally excited (LE) states at the NBN‐phenalenyl fragments, while that of 2 is dominated by charge transfer (CT) from the NBN‐phenalenyl to the p‐CF3‐C6H4 fragment. Depending on the dihedral angle θ between its Ph and NBN planes, compound 3 emits mainly from a less polar LE (θ >55°) or more polar CT state (θ <55°). In turn, the energetic preference for either state is governed by the polarity of the solvent used. An equimolar aggregate of the NBN‐ and BNB‐phenalenyls 3 and 6 (in THF/H2O) shows a distinct red‐shifted emission compared to that of the individual components, which originates from an intermolecular CT state. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Perovskite solar cells (PSCs) have been proven to be a promising option for photovoltaic conversion. With the aim to achieve efficient and stable PSCs, it is essential to explore dopant‐free hole‐transporting materials (HTMs) with high hole mobility. Herein, HTMs bearing electron donor (D)‐electron acceptor (A)‐electron donor (D) structures have been constructed with strong intramolecular charge transfer (ICT) effect, based on rational combination of dibenzo[a,c]phenazine and pyridine as electronic acceptors and anchoring groups to perovskite layer. Accordingly, high hole mobility (7.31 × 10–5 cm2·V–1·s–1) and photoelectric conversion efficiency (20.45%) have been achieved by dopant‐free DPyP‐based PSC. It afforded an efficient way to design HTMs with high hole mobility by adjustment of molecular configurations and electronic property of conjugated systems. [ABSTRACT FROM AUTHOR]

Reduction of chlorogermylene MsFluindtBth potassium graphite (KC8) afforded putative germylyne radical MsFluindtBu-Ge 2 as confirmed by electron paramagnetic resonance (EPR) spectroscopy. However, it slowly decayed via C--H bond activation at the fluorenyl moiety to yield a bis(germylene) 3 at room temperature. By using a Lewis base to stabilize the unoccupied p orbital at the GeI radical center, acyclic two-coordinate GeI radicals MsFluindtBu-Ge(IMe4) 4 (IMe4 = 1,3,4,5-tetramethyl-imidazolin-2-ylidene), MsFluindtBu-Ge(IiPr) 5 (IiPr = 1,3-diisopropyl-4,5-dimethyl-imidazolin-2-ylidene), MsFluindtBu-Ge(PMe3) 6 were isolated in crystalline forms. The unpaired electron in 4--6 mainly resides at the Ge 4p orbital as revealed by EPR spectroscopic studies and theoretical calculations. Interestingly, facile ligand exchange of PMe3 in 6 with IMe4 and IiPr was observed to afford 4 and 5, respectively. Moreover, phosphinogermylyne 6 reacted with PhEEPh (E = S, Se), 4-tetrabutylphenylacetylene (Ar'CCH), [CpMo(CO)3]2 and nBu3SnH to furnish germylenes MsFluindtBu-GeEPh (E = S 7, Se 8), MsFluindtBu-GeCH=CHAr' 9, a germylyne complex MsFluindtBu-Ge=Mo(CO)2Cp 10 and a Ge(IV) compound MsFluindtBu-GeH2SnnBu3 11, respectively. The reactivity studies demonstrate that 6 can act as a synthon of one-coordinate germylyne radical attributing to labile coordination of trimethylphosphine. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Owing to the function of manipulating light absorption distribution, tandem organic solar cells containing multiple sub‐cells exhibit high power conversion efficiencies. However, there is a substantial challenge in precisely controlling the inter‐subcells carrier migration which determines the balance of charge transport across the entire device. The conductivity of "nanowires"‐like conducting channel in interconnecting layer between sub‐cells should be improved which calls for fine engineering on the morphology of polyelectrolyte in interconnecting layer. Here, we develop a simple method to effectively manipulating the domains of conductive components in commercially available polyelectrolyte PEDOT:PSS. The use of poor solvent could effectively modify the configuration of polystyrene sulfonic acid and thus the space for conductive components. Based on our strategy, the insulated shells wrapping conductive domains are thinned and the efficiencies of tandem organic solar cells are improved. We believe our method might provide guidance for the manufacture of tandem organic solar cells. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Owing to the function of manipulating light absorption distribution, tandem organic solar cells containing multiple sub‐cells exhibit high power conversion efficiencies. However, there is a substantial challenge in precisely controlling the inter‐subcells carrier migration which determines the balance of charge transport across the entire device. The conductivity of "nanowires"‐like conducting channel in interconnecting layer between sub‐cells should be improved which calls for fine engineering on the morphology of polyelectrolyte in interconnecting layer. Here, we develop a simple method to effectively manipulating the domains of conductive components in commercially available polyelectrolyte PEDOT:PSS. The use of poor solvent could effectively modify the configuration of polystyrene sulfonic acid and thus the space for conductive components. Based on our strategy, the insulated shells wrapping conductive domains are thinned and the efficiencies of tandem organic solar cells are improved. We believe our method might provide guidance for the manufacture of tandem organic solar cells. [ABSTRACT FROM AUTHOR]

Reactions of dimethyl 2‐arylcyclopropane‐1,1‐dicarboxylates, used as representatives of D‐A cyclopropanes, with tropothione were carried out in the presence of scandium triflate as a catalyst, under mild conditions (CH2Cl2 solution, rt). The anticipated (8+3)‐cycloaddition products, cycloheptatriene fused thiopyrans, were obtained in good to excellent yields. Cycloadditions occurred with complete diastereoselectivity and in all cases single diastereomers were formed. Structures of isolated cycloadducts were established based on spectroscopic data and in two cases they were unambiguously confirmed by single crystal X‐ray diffraction analysis. In contrast to an analogous (8+3)‐cycloaddition reported for parent tropone, which was performed in the presence of Ni(ClO4)2, no 1,3‐H shift leading to products possessing a CH2 moiety located within the seven‐membered ring was observed. [ABSTRACT FROM AUTHOR]

Organic ferroelectric (FE) materials, though known for more than a century, are yet to reach close to the benchmark of inorganic or hybrid materials in terms of the magnitude of polarization. Amongst the different classes of organic systems, donor (D)–acceptor (A) charge‐transfer (CT) complexes are recognized as promising for ferroelectricity owing to their neutral‐to‐ionic phase transition at low temperature. This review presents an overview of different supramolecular D‐A systems that have been explored for FE phase transitions. The discussion begins with a general introduction of ferroelectricity and its different associated parameters. Then it moves on to show early examples of CT cocrystals that have shown FE properties at sub‐ambient temperature. Subsequently, recent developments in the field of room temperature (RT) ferroelectricity, exhibited by H‐bond‐stabilized lock‐arm supramolecular‐ordering (LASO) in D‐A co‐crystals or other FE CT‐crystals devoid of neutral‐ionic phase transition are discussed. Then the discussion moves on to emerging reports on other D‐A soft materials such as gel and foldable polymers; finally it shows very recent developments in ferroelectricity in supramolecular assemblies of single‐component dipolar or ambipolar π‐systems, exhibiting intra‐molecular charge transfer. The effects of structural nuances such as H‐bonding, balanced charge transfer and chirality on the observed ferroelectricity is described with the available examples. Finally, piezoelectricity in recently reported ambipolar ADA‐type systems are discussed to highlight the future potential of these soft materials in micropower energy harvesting. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The development of host‐guest MOF luminescent composites has attracted considerable attention. However, it is still a challenge to reasonably design large scale conjugated polycarboxylic acids metal‐organic framework (MOF) and modulate donor‐acceptor interaction. Herein, a series of isostructural 3D porous lanthanide MOF [Ln2(BINDI)0.5(NO3)(DMA)(H2O)]∙DMA∙2.5H2O (Ln = La (1), Ce (2), Pr (3) and Nd (4); H4BINDI (N,N'‐bis(5‐isophthalic acid)‐1,4,5,8‐naphthalenediimide) were synthesized. Considering the electron‐deficient performances of Ln‐BINDI MOFs, D‐A type composites Ln‐MOFs (1—4@H4TBAPy) were prepared via the incorporation of electron‐rich H4TBAPy (1,3,6,8‐tetrakis(p‐benzoic acid) pyrene), which more improved the luminescence performance of complexes 1—4 and can be used as fluorescence sensors for the detection of nitro compounds and aldehydes. High sensitivity of 1@H4TBAPy towards pNBA, pNA PNP, DNP, and TNP could be achieved through hydrogen bond interactions between MOF and analytes, as well as the π‐π interaction between H4TBAPy and the naphthalene ring of BINDI, thus the fluorescence quenching efficiency of 1@H4TBAPy was better than that of the complex 1. In addition, it is found that 1@H4TBAPy has high selectivity and sensitivity to aromatic aldehyde SA, 5‐Mesal and HMBA. Such strategy to enhance the emission of NDI based Ln‐BINDI MOFs, will open up an avenue to obtain more fluorescent MOFs for sensing. [ABSTRACT FROM AUTHOR]

The Photophysical properties, such as fluorescence quenching, and photoexcitation dynamics of bimolecular non-covalent systems consisting of cationic poly[(9,9-di(3,3′-N,N′-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and anionic graphene carboxylate (GC) have been discovered for the first time via steady-state and time-resolved femtosecond transient absorption (TA) spectroscopy with broadband capabilities. The steady-state fluorescence of PFN is quenched with high efficiency by the GC acceptor. Fluorescence lifetime measurements reveal that the quenching mechanism of PFN by GC is static. Here, the quenching mechanisms are well proven via the TA spectra of PFN/GC systems. For PFN/GC systems, the photo electron transfer (PET) and charge recombination (CR) processes are ultrafast (within a few tens of ps) compared to static interactions, whereas for PFN/1,4-dicyanobenzene DCB systems, the PET takes place in a few hundreds of ps (217.50 ps), suggesting a diffusion-controlled PET process. In the latter case, the PFN+•–DCB−• radical ion pairs as the result of the PET from the PFN to DCB are clearly resolved, and they are long-lived. The slow CR process (in 30 ns time scales) suggests that PFN+• and DCB−• may already form separated radical ion pairs through the charge separation (CS) process, which recombine back to the initial state with a characteristic time constant of 30 ns. The advantage of the present positively charged polyfluorene used in this work is the control over the electrostatic interactions and electron transfers in non-covalent polyfluorene/quencher systems in DMSO solution. [ABSTRACT FROM AUTHOR]

Merocyanines, thanks to their easily adjustable electronic structure, appear to be the most versatile and promising functional dyes. Their D–π–A framework offers ample opportunities for custom design through variations in both donor/acceptor end‐groups and the π‐conjugated polymethine chain, and leads to a broad range of practical properties, including noticeable solvatochromism, high polarizability/hyperpolarizabilities, and the ability to sensitize various physicochemical processes. Accordingly, merocyanines are applied and extensively studied in various fields, such as light‐converting materials for optoelectronics, nonlinear optics, optical storage, solar cells, fluorescent probes, and antitumor agents in photodynamic therapy. This review encompasses both classical and novel more important publications on the structure–property relationships in merocyanines, with particular emphasis on the results by A. I. Kiprianov and his followers in Institute of Organic Chemistry in Kyiv, Ukraine. [ABSTRACT FROM AUTHOR]

Cycloparaphenylenes (CPPs) are the smallest possible armchair carbon nanotubes, the properties of which strongly depend on their ring size. They can be further tuned by either peripheral functionalization or by replacing phenylene rings for other aromatic units. Here we show how four novel donor–acceptor chromophores were obtained by incorporating fluorenone or 2‐(9H‐fluoren‐9‐ylidene)malononitrile into the loops of two differently sized CPPs. Synthetically, we managed to perform late‐stage functionalization of the fluorenone‐based rings by high‐yielding Knoevenagel condensations. The structures were confirmed by X‐ray crystallographic analyses, which revealed that replacing a phenylene for a fused‐ring‐system acceptor introduces additional strain. The donor–acceptor characters of the CPPs were supported by absorption and fluorescence spectroscopic studies, electrochemical studies (displaying the CPPs as multi‐redox systems undergoing reversible or quasi‐reversible redox events), as well as by computations. The oligophenylene parts were found to comprise the electron donor units of the macrocycles and the fluorenone parts the acceptor units. [ABSTRACT FROM AUTHOR]

Leveraging the unique reactivity profile of donor-acceptor aminocyclopropanes and cyclobutanes allows the preparation of complex nitrogen-substituted molecules. While most reports focus on donor-acceptor strained rings with two geminal carbonyl groups as acceptors, mono carbonyl acceptor systems, despite their synthetic relevance, have been considerably less studied. Herein we describe catalytic annulation reactions ofaminocyclopropane and aminocyclobutane monoesters employing silylium catalysis to activate these less reactive donor-acceptor systems.

Comprehensive Summary: Energy levels and energy level alignment at interfaces play a decisive role in designing efficient and stable organic solar cells (OSCs). In this review two usually used technologies in organic photovoltaic communities for measuring energy levels of organic semiconductors, photoelectron spectroscopy and electrochemical methods, are introduced, and the relationships between the values obtained from the corresponding techniques are compared. The energy level and energy level alignment across the interfaces involved in solution processed organic photovoltaics are described, and the corresponding integer charge transfer model for predicting and explaining energy level alignment is presented. The effects of the interface properties in designing efficient binary and ternary OSCs were discussed. The effects of environmental factors mainly including water vapor, oxygen gas and thermal annealing on energy levels and energy level alignment involved in photoactive layers, and the subsequent effects on the corresponding OSC properties are given. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Energy levels and energy level alignment at interfaces play a decisive role in designing efficient and stable organic solar cells (OSCs). In this review two usually used technologies in organic photovoltaic communities for measuring energy levels of organic semiconductors, photoelectron spectroscopy and electrochemical methods, are introduced, and the relationships between the values obtained from the corresponding techniques are compared. The energy level and energy level alignment across the interfaces involved in solution processed organic photovoltaics are described, and the corresponding integer charge transfer model for predicting and explaining energy level alignment is presented. The effects of the interface properties in designing efficient binary and ternary OSCs were discussed. The effects of environmental factors mainly including water vapor, oxygen gas and thermal annealing on energy levels and energy level alignment involved in photoactive layers, and the subsequent effects on the corresponding OSC properties are given. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescence (TADF) materials have shown great potential in the design of organic metal‐free optoelectronic devices and materials and, therefore, are the subject of intense investigations. This contribution presents the effects of various parameters on the photophysical properties of a series of boron‐based TADF emitters. These include torsion angle, the changes in the electronic density, energy gap between the first excited singlet (S1) and the first excited triplet states (T1), oscillator strength (f) and spin‐orbit coupling (SOC). Through a comprehensive structural analysis, we first show the most favorable conformation of the ground state of donor (D) and acceptor (A) moieties that are popular in TADF emitters. Further, the properties of the excited state manifolds are obtained with Tamm‐Dancoff Approximation (TDA), thus rationalizing their optical and photophysical properties. Globally, our results settle the basis for the rationalization of the effects of different parameters on reverse intersystem crossing (RISC) probabilities, which is the rate‐limiting step for TADF, thus favoring the rational design of novel highly efficient TADF materials with strong triplet exciton harvesting. [ABSTRACT FROM AUTHOR]

Partial charge fluctuations in the charge‐ordered state of a material, often triggered by structural disorders and/or defects, can significantly alter its physical characteristics, such as magnetic long‐range ordering. However, it is difficult to post‐chemically fix such accidental partial fluctuations to reconstruct a uniform charge‐ordered state. Herein, we report CO2‐aided charge ordering demonstrated in a CO2‐post‐captured layered magnet, [{Ru2(o‐ClPhCO2)4}2{TCNQ(OMe)2}] ⋅ CO2 (1⊃CO2; o‐ClPhCO2−=ortho‐chlorobenzoate; TNCQ(OMe)2=2,5‐dimethoxy‐7,7,8,8‐tetracyanoquinodimethane). Pristine porous layered magnet 1 had a partially charge‐fluctuated ordered state, which provided ferrimagnetic ordering at TC=65 K. Upon loading CO2, 1 adsorbed one mole of CO2, forming 1⊃CO2, and raising TC to 100 K. This was because of the vanishing charge fluctuations without significantly changing the framework structure. This research illustrates the post‐accessible host–guest chemistry delicately combined with charge, spin, and lattice ordering in a spongy magnet. Furthermore, it highlights how this innovative approach opens up new possibilities for technology and nanoscale magnetism manipulation. [ABSTRACT FROM AUTHOR]

Four A‐π‐D‐π‐A type small organic molecules with 1,8‐naphthalimide motifs were successfully synthesised. The designed compounds are built of two 1,8‐naphthalimide units linked via ethynyl π‐linkages with selected functionalised donor motifs i. e. 2,2'‐bithiophene, fluorene, phenothiazine and carbazole derivative. The synthesis based on Sonogashira cross‐coupling allowed us to obtain the presented dyes with good yields. The resulting symmetrical small molecules' optical, electrochemical and thermal properties were thoroughly investigated, and their potential applicability for the OLED devices was demonstrated. In addition, the relationship between molecular structure and properties was considered by employing experimental and theoretical studies. As a result of using various donor groups, it was possible to achieve efficient electroluminescence in the range from green (DEV4) to orange‐red light (DEV3) with a maximum luminance of 3 820 cd/m2 for DEV4. Upon the insertion of an acetylene linker to the designed molecules, the free rotation of D and A fragments, and hence the effective π‐electron communication within the entire molecule, is possible, which was confirmed by DFT studies. The obtained dyes are characterised by high thermal stability, reversible oxidation‐reduction process, satisfactory optoelectronic properties and good solubility in organic solvents, which is advisable for the application in small molecular organic light‐emitting diodes (SM‐OLEDs) technology. [ABSTRACT FROM AUTHOR]

Partial charge fluctuations in the charge‐ordered state of a material, often triggered by structural disorders and/or defects, can significantly alter its physical characteristics, such as magnetic long‐range ordering. However, it is difficult to post‐chemically fix such accidental partial fluctuations to reconstruct a uniform charge‐ordered state. Herein, we report CO2‐aided charge ordering demonstrated in a CO2‐post‐captured layered magnet, [{Ru2(o‐ClPhCO2)4}2{TCNQ(OMe)2}] ⋅ CO2 (1⊃CO2; o‐ClPhCO2−=ortho‐chlorobenzoate; TNCQ(OMe)2=2,5‐dimethoxy‐7,7,8,8‐tetracyanoquinodimethane). Pristine porous layered magnet 1 had a partially charge‐fluctuated ordered state, which provided ferrimagnetic ordering at TC=65 K. Upon loading CO2, 1 adsorbed one mole of CO2, forming 1⊃CO2, and raising TC to 100 K. This was because of the vanishing charge fluctuations without significantly changing the framework structure. This research illustrates the post‐accessible host–guest chemistry delicately combined with charge, spin, and lattice ordering in a spongy magnet. Furthermore, it highlights how this innovative approach opens up new possibilities for technology and nanoscale magnetism manipulation. [ABSTRACT FROM AUTHOR]

Organic solar cells have been continuously studied and developed through the last decades. A major step in their development was the introduction of fused‐ring non‐fullerene electron acceptors. Yet, beside their high efficiency, they suffer from complex synthesis and stability issues. Perylene‐based non‐fullerene acceptors, in contrast, can be prepared in only a few steps and display good photochemical and thermal stability. Herein, we introduce four monomeric perylene diimide acceptors obtained in a three‐step synthesis. In these molecules, the semimetals silicon and germanium were added in the bay position, on one or both sides of the molecules, resulting in asymmetric and symmetric compounds with a red‐shifted absorption compared to unsubstituted perylene diimide. Introducing two germanium atoms improved the crystallinity and charge carrier mobility in the blend with the conjugated polymer PM6. In addition, charge carrier separation is significantly influenced by the high crystallinity of this blend, as shown by transient absorption spectroscopy. As a result, the solar cells reached a power conversion efficiency of 5.38 %, which is one of the highest efficiencies of monomeric perylene diimide‐based solar cells recorded to date. [ABSTRACT FROM AUTHOR]

A set of novel 1,4-diaryl-1,3-butadiynes terminated by two 7-(arylethynyl)-1,8-bis(dimethylamino)naphthalene fragments was prepared via the Glaser–Hay oxidative dimerization of 2-ethynyl-7-(arylethynyl)-1,8-bis(dimethylamino)naphthalenes. The oligomers synthesized in this way are cross-conjugated systems, in which two conjugation pathways are possible: π-conjugation of 1,8-bis(dimethylamino)naphthalene (DMAN) fragments through a butadiyne linker and a donor–acceptor aryl–C≡C–DMAN conjugation path. The conjugation path can be “switched” simply by protonation of DMAN fragments. X-ray diffraction, UV–vis spectroscopy and cyclic voltammetry are applied to analyze the extent of π-conjugation and the efficiency of particular donor–acceptor conjugation path in these new compounds. X-ray structures and absorption spectra of doubly protonated tetrafluoroborate salts of the oligomers are also discussed.

Donor–acceptor-substituted biphenyl derivatives are particularly interesting model compounds, which exhibit intramolecular charge transfer because of the extent of charge transfer between both substituents. The connection of a 4-[1,1′-biphenyl]-4-yl-2-pyrimidinyl) moiety to differently disubstituted amino groups at the biphenyl terminal can offer push–pull compounds with distinctive photophysical properties. Herein, we report a comprehensive study of the influence of the torsion angle of the disubstituted amino group on the emissive properties of two pull–push systems: 4-[4-(4-N,N-dimethylaminophenyl)phenyl]-2,6-diphenylpyrimidine (D1) and 4-[4-(4-N,N-diphenylaminophenyl)phenyl]-2,6-diphenylpyrimidine (D2). The torsion angle of the disubstituted amino group, either N,N-dimethyl-amine or N,N-diphenyl-amine, at the biphenyl end governs their emissive properties. A drastic fluorescence quenching occurs in D1 as the solvent polarity increases, whereas D2 maintains its emission independently of the solvent polarity. Theoretical calculations on D1 support the presence of a twisted geometry for the lowest energy, charge-transfer excited state (S1,90), which corresponds to the minimum energy structure in polar solvents and presents a small energy barrier to move from the excited to the ground state, thereby favoring the non-radiative pathway and reducing the fluorescence efficiency. In contrast, this twisted structure is absent in D2 due to the steric hindrance of the phenyl groups attached to the amine group, making the non-radiative decay less favorable. Our findings provide insights into the crucial role of the substituent in the donor moiety of donor–acceptor systems on both the singlet excited state and the intramolecular charge-transfer process.

Acepleiadylene (APD), a nonbenzenoid isomer of pyrene, exhibits a unique charge‐separated character with a large molecular dipole and a small optical gap. However, APD has never been explored in optoelectronic materials to take advantage of these appealing properties. Here, we employ APD as a building block in organic semiconducting materials for the first time, and unravel the superiority of nonbenzenoid APD in electronic applications. We have synthesized an APD derivative (APD‐IID) with APD as the terminal donor moieties and isoindigo (IID) as the acceptor core. Theoretical and experimental investigations reveal that APD‐IID has an obvious charge‐separated structure and enhanced intermolecular interactions as compared with its pyrene‐based isomers. As a result, APD‐IID displays significantly higher hole mobilities than those of the pyrene‐based counterparts. These results imply the advantages of employing APD in semiconducting materials and great potential of nonbenzenoid polycyclic arenes for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Phosphonium‐based compounds gain attention as promising photofunctional materials. As a contribution to the emerging field, we present a series of donor‐acceptor ionic dyes, which were constructed by tailoring phosphonium (A) and extended π‐NR2 (D) fragments to an anthracene framework. The alteration of the π‐spacer of electron‐donating substituents in species with terminal −+PPh2Me groups exhibits a long absorption wavelength up to λabs=527 nm in dichloromethane and shifted the emission to the near‐infrared (NIR) region (λ=805 nm for thienyl aniline donor), although at low quantum yield (Φ<0.01). In turn, the introduction of a P‐heterocyclic acceptor substantially narrowed the optical bandgap and improved the efficiency of fluorescence. In particular, the phospha‐spiro moiety allowed to attain NIR emission (797 nm in dichloromethane) with fluorescence efficiency as high as Φ=0.12. The electron‐accepting property of the phospha‐spiro constituent outperformed that of the monocyclic and terminal phosphonium counterparts, illustrating a promising direction in the design of novel charge‐transfer chromophores. [ABSTRACT FROM AUTHOR]

The bromine‐lithium exchange‐borylation‐Suzuki sequence efficiently furnishes phenothiazine‐terephthalonitrile donor‐acceptor dyads and triads in high yields. In contrast to most phenothiazine‐acceptor conjugates the title compounds are ligated in p‐position to the phenothiazine nitrogen atom. Moreover, the acceptors are either directly linked or ligated by an arylene bridge and p‐anisyl N‐substituents on the phenothiazine are chosen to lock the tricycle into an intra‐configuration. Cyclic voltammetry reveals effects of bridging and ligation of the N‐substituent. Optical spectroscopy likewise displays similar band gaps, large Stokes shifts and substantial to high quantum yields in solution, in the solid state and in PMMA matrix. Time‐resolved fluorescence spectroscopy indicates quite long fluorescence decay times in solution and emission components in the microsecond time range. TADF properties are further assessed by fluorescence increase in deoxygenated solution, gated emission spectroscopy and temperature‐dependent determination of phosphorescence. The nature of the electronically excited states is investigated by DFT/MRCI. While for the directly ligated dyad a singlet‐triplet energy gap ΔE(S1-T1) ${{E}_{{({\rm S}}_{1}-{{\rm T}}_{1})}{\rm \ }}$ of 0.24 eV can be estimated and is consistently confirmed by quantum chemical calculations on the lowest energy conformer, even lower ΔE(S1-T1) ${{\rm \Delta }{E}_{{(S}_{1}-{T}_{1})}{\rm \ }}$ of 0.029 and 0.008 eV are estimated for the investigated dyads and the triad in the solid state and in PMMA matrix. [ABSTRACT FROM AUTHOR]

2,6‐Bis(pyrrol‐2‐yl)pyridines are important building blocks for supramolecular assemblies and photoluminescent main group and transition metal compounds. Sterically encumbered 2,6‐bis(5‐(2,4,6‐trimethylphenyl)‐3‐phenyl‐1H‐pyrrol‐2‐yl)pyridine, H2MesPDPPh, can adopt monomeric and dimeric structures in the solid state and in solution, controlled by competing inter‐ and intramolecular hydrogen bonds. Deprotonation in the presence of lithium cations provides Li2MesPDPPh, which can be isolated in monomeric and dimeric forms depending on solvent polarity. Protonation of H2MesPDPPh disrupts intramolecular hydrogen bonding and provides the monomeric pyridinium salt [H3MesPDPPh]Cl. Independent of solvent polarity, all three derivatives exhibit intense fluorescence in solution. The absorption and emission spectra are highly sensitive to the level of protonation, which can be rationalized by the effects of (de)protonation on the HOMO and LUMO of the tricyclic π‐system. [ABSTRACT FROM AUTHOR]

An amino‐ene click reaction is a type of aza‐Michael addition reaction that is congruent with click chemistry in terms of its reaction efficiency and rate under mild conditions. The amino‐ene click reaction is increasingly recognized as a prominent synthetic tool to form C−N bonds in the context of organic materials chemistry and polymer chemistry. Herein, an unconventional amino‐ene click reaction with negative activation enthalpies, in which an electron‐deficient π‐conjugated molecule, such as a naphthalenediimide, reacts with an amine faster at lower temperatures is reported. The detailed study of the reaction mechanism reveals that the amino‐ene click reaction proceeds via a pre‐equilibrium reaction, the key to which is the formation of a stable reaction intermediate due to the solvation and charge delocalization on the π‐core. By optimizing the reaction conditions, it was demonstrated that the amino‐ene click reaction proceeded faster at 273 K than at 347 K, which was easily observed visually. [ABSTRACT FROM AUTHOR]

Herein, donor (D)‐acceptor (A) type fluorophores (TTBz and TTNz) were designed and synthesized with different acceptor units. The two acceptor units benzo[c][1,2,5]thiadiazole (Bz) and naphtho[2,3‐c][1,2,5]thiadiazole (Nz) are asymmetrically functionalized with triphenylamine (TPA) as a strong donor and tetraphenylethylene (TPE) as an aggregation‐induced emission (AIE)‐luminogen to realize combined AIE and hybridized local and charge transfer (HCLT) excited state features as well as long‐wavelength emission. Their HCLT and AIE properties are verified by theoretical calculations, solvatochromic effects, and transient photoluminescence decay experiments. They exhibit strong orange‐red and deep‐red fluorescence emission with good thermal stability and hole mobility, leading to effective utilization as emitters in organic light‐emitting diodes (OLEDs). The resulting devices show decent electroluminescent (EL) performance (current efficiency of 12.04–12.58 cd A−1, maximum brightness of 11206–20160 cd m−2, and external quantum efficiency of 5.11–5.47 %). Particularly, the TTNz‐based OLED demonstrates steady deep‐red emission with a peak at 661 nm and CIE coordinates of (0.67, 0.33). [ABSTRACT FROM AUTHOR]

Homoconjugated push–pull chromophores were obtained by an efficient, click-type formal [2+2] cycloaddition. With these short synthetic transformations, complex chromophore structures were achieved in a single step without any by-product formation. Significant second-order optical nonlinearities have been calculated for the synthesized compounds.

Donor–π–acceptor fluorophores that consist of an electron‐donating amino group and an electron‐accepting triarylborane moiety generally exhibit substantial solvatochromism in their fluorescence while retaining high fluorescence quantum yields even in polar media. Herein, we report a new family of this compound class, which bears ortho‐P(=X)R2‐substituted phenyl groups (X=O or S) as a photodissociative module. The P=X moiety that intramolecularly coordinates to the boron atom undergoes dissociation in the excited state, giving rise to dual emission from the corresponding tetra‐ and tricoordinate boron species. The susceptibility of the systems to photodissociation depends on the coordination ability of the P=O and P=S moieties, whereby the latter facilitates dissociation. The intensity ratios of the dual emission bands are sensitive to environmental parameters, including temperature, solution polarity, and the viscosity of the medium. Moreover, precise tuning of the P(=X)R2 group and the electron‐donating amino moiety led to single‐molecule white emission in solution. [ABSTRACT FROM AUTHOR]

A convenient one‐step synthesis of β‐aminocyclobutane monoesters starting from commercially available reagents is reported. The obtained strained rings undergo (4+2) dearomative annulation with indole partners using silylium catalysis. This organocatalyzed annulation provided tricyclic indolines with four new stereocenters in up to quantitative yield and >95 : 5 diastereoselectivity and can proceed both intra‐ and intermolecularly. When performed intramolecularly, the tetracyclic structure of either akuamma or malagasy alkaloids was obtained selectively depending on the temperature of the reaction. This divergent outcome could be rationalized based on DFT calculations. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The visible light‐driven C2 or C3 amination of indoles without any additives was initiated via electron donor‐acceptor (EDA) complex formed by indole and N‐aminopyridinium salt. This method was compatible with a wide range of substrates and could proceed smoothly without the addition of any photocatalysts, transition‐metal catalysts, or bases. A variety of studies were carried out to examine the presence of EDA complex. [ABSTRACT FROM AUTHOR]

Adrenaline, also known as epinephrine, is a neurotransmitter/hormone that is an important target in diagnostics. Development of an effective method for detecting it in the presence of other neurotransmitters is a challenging task. The electrochemical and fluorescent techniques commonly used have low selectivity in distinguishing among catecholamines. Herein, a small‐molecule organic probe with an activated furfural moiety is reported to exploit the nucleophilicity of epinephrine to generate a bright‐colored donor–acceptor Stenhouse adduct. Among nine common neurotransmitters or their analogues, only epinephrine was found to generate a unique colour change discernible with the naked eye, whereas the other ones remain unaffected. Under various in‐field detection conditions, including solution, droplet, and paper strip‐based detection, the colour change were also noticeable. The low detection limit of 1.37 nM and a limit of quantitation of 4.37 nM were achieved with simple UV/Vis methods in addition to the sub‐ppm level sensing under visual conditions with naked eyes. The probe could be used for practical colorimetric measurements as a point‐of‐care tool without any complex and expensive machinery, making this approach accessible to all. In addition, using a simple smartphone, the determination of epinephrine concentrations is possible by using machine‐learning techniques. [ABSTRACT FROM AUTHOR]

Ferrocene‐BODIPY (Fc‐BDP) conjugates in which one or two ferrocene entities are linked to the β‐positions of the BODIPY core by an ethynyl bridge have been developed. These derivatives were easily and efficiently grafted onto a dual‐clickable fullerene platform using CuAAC reactions, leading to a clickable Fc‐BDP‐C60 triad and a clickable [Fc]2‐BDP‐C60 tetrad which can be used for further derivatization with complex structures. Due to the extended π‐conjugation and the presence of an intramolecular charge transfer band from Fc to BDP, all these conjugates display a broad absorption in the visible region, which is bathochromically shifted when two Fc are appended to the BDP core. Ultrafast multistep electron transfers leading to charge stabilization were demonstrated in the Fc‐BDP‐C60 triad and [Fc]2‐BDP‐C60 tetrad by femtosecond transient absorption studies. [ABSTRACT FROM AUTHOR]

Porphyrins and their derivatives have been employed extensively in organic solar cells (OSCs) in recent years. However, a deeper understanding of the exciton dissociation process for the porphyrin donor/non‐fullerene acceptor (NFA) interface is still lacking. Herein, we have combined quantum chemistry and molecular dynamics simulations to explore the combination of mono and dimer porphyrin donors with various types of NFAs. The work reveals that the key issue lies in the exciton dissociation process of porphyrin materials, which have strong crystallinity to increase spacing (more than 5.0 Å), resulting in lesser miscibility and weaker intermolecular π‐π stacking. The pathway for exciton dissociation will be limited by the small number of high‐energy charge transfer (CT) states. To solve the above‐mentioned issues, we implement an improved strategy for modifying the side chain of the terminal unit, reducing the stacking distance to 4.4 Å, while the number of CT states reaches up to 40 % (3/A3 style 1). Additionally, the results also indicate the development potential for all porphyrin OSCs, particularly, the charge recombination (kCR) rate of the 1/Rf‐Iso system is lowered by nearly nine orders of magnitude. This research may offer fresh perspectives for extending the application range of porphyrin materials in OSCs. [ABSTRACT FROM AUTHOR]

Donor‐acceptor‐π bridge‐acceptor (D−A−π−A) motif dyes are promising dye sensitizers in dye‐sensitized solar cells (DSSCs). In this study, to strengthen with‐drawing electron force of the auxiliary electron acceptors(A) in D−A−π−A motif dye sensitizers, the metal complexes unit is be used as auxiliary electron acceptor(A) instead of organic electron‐withdrawing monomer. The four polymeric metal complexes were designed, synthesized, and characterized, which used metal complexes of phenanthroline derivatives as auxiliary acceptors (A), benzodithiophene‐dithiophene derivatives (BDTT) as donors (D), and 8‐hydroxyquinoline derivatives as π‐bridges and acceptors of the dye sensitizers, and have been used for dye sensitizers. Under AM 1.5 G (100 mW cm−2), the photovoltaic test results indicated that the short‐circuit photocurrent density (Jsc) of the DSSCs based four polymeric metal complexes are 11.26, 13.68, 14.42 and 15.57 mA cm−2 and power conversion efficiency (PCE) are 5.96 %, 7.83 %, 8.07 %, 9.28 % respectively. Both Jsc and PCE value of the four polymeric metal complexes increased in order. This may be due to the fact that larger radius of metal ion under the same change number can enhance the coordination bond and cause stronger electron‐withdrawing ability of auxiliary acceptor and stronger charge‐transfer ability between the donor and the acceptor, which results in higher Jsc and higher PCE of the polymeric complex dye sensitizer. [ABSTRACT FROM AUTHOR]

As new polycyclic aromatic hydrocarbons (PAHs) containing an imide group, we designed and synthesized 2,3‐naphthalimide fused with benzothiophene 1 or benzofuran 2. 1 and 2 have a push‐pull structure attributed to the imide group and the electron‐donating heterocyclic moieties, indicated that 1 and 2 play as a fluorosolvatochromic dye. 1 and 2 were synthesized in 3‐steps. The absorption and fluorescence spectra were measured in twelve different solvents. The absorption spectra of 1 and 2 showed a slight solvent dependence. On the other hand, a strong solvent dependence was observed in the fluorescence spectra of 1 and 2, that is, fluorosolvatochromism. The plots of the emission maximum versus the solvent polarity parameter ET(30) for 1 and 2 exhibited a good linear correlation. Multiple linear regression analysis using Catalán scale suggested that the fluorescence behavior of 1 and 2 is influenced by the acidity and dipolarity of the solvents. The changes in the dipole moment between the ground and excited states estimated by the Lippert‐Mataga equation were 7.6 D for 1 and 7.2 D for 2. [ABSTRACT FROM AUTHOR]

This study reports an effective peripheral decoration of organic donor‐acceptor diads with B(C6F5)3 for stabilizing electrogenerated radical ions. By employing a common p‐type organic semiconductor benzothienobenzothiophene (BTBT) as the donor, tetracoordinate boron complexes showed improved solution electrochemiluminescence (ECL) intensity, reaching a 156‐fold increase compared to that of the parent diad. The unprecedented Lewis‐pairing‐induced ECL enhancement is attributed to the multiple roles of B(C6F5)3: 1) redistributing frontier orbitals, 2) facilitating electrochemical excitation, and 3) restricting molecular motions. Furthermore, B(C6F5)3 converted the molecular arrangement of BTBT from conventional 2D herringbones into 1D π‐stacks. This robust, highly ordered columnar nanostructure allowed red‐shifting of the crystalline film ECL with electrochemical doping through the electronic coupling pathways of BTBT. Our approach will facilitate the development of elaborate metal‐free ECL systems. [ABSTRACT FROM AUTHOR]

Azines are interesting compounds exhibiting aggregation‐induced‐emission (AIE) and twisted‐intramolecular‐charge‐transfer (TICT) properties that have exciting prospects in chemosensing and bioimaging applications. They commonly have symmetrical structures and there is no report on red‐emissive unsymmetrical azines. Herein, we report a novel class of orange‐to‐red emissive hydroxybenzothiazole(HBT)‐based unsymmetrical azines (BTDPA) with triple photophysical characteristics of ESIPT‐TICT‐AIE. The dyes were synthesized by an all‐throughout mechanochemical route in a sustainable way. They displayed D1‐A‐D2 character and fluoresce strongly both in organic solvents due to ESIPT and in the solid state by AIE via TICT. The incorporation of different electron‐withdrawing groups (EWGs) and electron‐donating groups (EDGs) at either HBT or diphenyl‐methylene moiety resulted in tunable fluorescence properties. The red‐emissive character was achieved by keeping EDG both at HBT (−OMe) and the diphenyl‐methylene moiety (−NMe2) (λem 680 nm). The dyes exhibited good quantum yields, large Stoke shifts (upto 293 nm) and were utilized in nitroaromatics and Cu2+ sensing. [ABSTRACT FROM AUTHOR]

Designing optimized systems for triplet‐triplet annihilation upconversion (TTA‐UC) with high UC emission efficiency at low power densities remains challenging. To improve the lifetime of triplet photosensitizers for TTA‐UC, donor‐acceptor‐heavy atoms were used to synthesize rotationally restricted PY‐MBD‐BR and unrestricted PY‐BD‐BR photosensitizers. The singlet oxygen quantum yields of both photosensitizers was ≈0.60 due to their structural similarity, except for the degree of rotation between the donor and acceptor. The triplet lifetime of PY‐BD‐BR and PY‐MBD‐BR was 352 μs and 1,503 μs, respectively. The latter may be among the highest reported for BODIPY photosensitizers. The prolonged triplet lifetime enabled excellent green‐to‐blue upconversion emission of PY‐MBD‐BR, with a high upconversion emission efficiency (ηUC) of 8.8 % and low threshold intensity (Ith) of 90 mW/cm2 compared to PY‐BD‐Br (low ηUC of 4.0 % and high Ith of 381 mW/cm2). The rigid molecular design of triplet photosensitizers based on donor‐acceptor‐heavy atom systems has potential for efficient TTA‐UC. [ABSTRACT FROM AUTHOR]