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Electrochromic (EC) smart windows are an elegant alternative to dusty curtains, blinds, and traditional dimming devices. The EC energy storage smart windows and displays received remarkable attention in the optoelectronic industry as they hold promise for high energy efficiency, low power consumption, reversibility, and swift response to stimuli. However, achieving these properties remains challenging. Moreover, most EC molecules do not exhibit electrofluorochromism, which is highly essential for smart displays because its EC property can modulate the solar heat entering the building, and its electrofluorochromic (EFC) aspects can create lighting during the night. In this work, a structure‐property relationship is utilized to develop new electrochromes that can store the injected charge, and these molecules indeed exhibit electrofluorochromism. The compounds are synthesized from tetrabenzofluorene with two aromatic acceptor units, and avoids the use of widely studied heterocycles and amine derivatives. The electrochromes switches from yellow to dark hue in solution, solid, and gel state. The compounds display exceptional electrochemical stability and reversibility in 1000 cycles and capacity retention of 93–100 % in 300 charging‐discharging cycles. The proof‐of‐concept device fabrication of the self‐dimming EC smart window presented here demonstrates that it can furnish visual comfort, modulate transmitted light and glare, and reduce energy usage. [ABSTRACT FROM AUTHOR]

Distyrylbenzenes (DSBs) are well‐known for their strong multicolour fluorescence. Fluorescence tuning of DSB via further functionalization/arylation, on the other hand, is uncommon. This paper reports a Pd‐catalysed direct arylation approach for introducing different aryl groups onto fluorobenzene‐containing DSB moiety (7) in high yields (67–72 %). The versatile methodology allows the substitution of neutral [tolyl (1)], electron‐deficient [p‐formyl benzene (2), p‐acetyl benzene (3), p‐nitrobenzene (4)] and electron‐rich [carbazole (5), triphenylamine (6)] aryl groups. The electron‐deficient aryls render mono‐substitution, while the electron‐rich counterparts promote di‐substitution. The compounds (1–6) show blue, green, and yellow fluorescence in both the solution and solid states; the fluorescence quantum yields reach >98 % and the peak maxima span from 425 to 560 nm. The mono‐carbazole DSB (5) exhibit white light emission (WLM) in polar solvents (acetone, DMF, CH3CN, DMSO and NMP) with very high fluorescence quantum yields (φf) of 60–80 %. For WLM, such high efficiency (φf) is somewhat uncommon. Moreover, visible‐to‐NIR reversible electrochromism is demonstrated by the TPA‐integrated DSB (6). The colour of 6 changes from pristine light yellow to orange, and the absorption maxima shifts from 372 to 1500 nm when a positive potential of 1.0 V vs Ag/Ag+ is applied. Moreover, the system shows high colouration efficiency in the NIR region with fast switching speeds for colouration and decolouration as fast as 0.98 s and 1.05 s. [ABSTRACT FROM AUTHOR]

Mesoionic carbenes (MIC) are a popular class of compound that are heavily investigated at the moment. The access to cationic MICs, and the ability of MICs to stabilize radicals are two highly attractive fields that have hardly been explored until now. Here the synthesis and characterisation of three different cationic azide‐substituted 1,2,3‐triazolium salts, used as building blocks for studying their reactivity towards triphenylphosphine are reported, where the reactivity is dependent on the nature of the starting triazolium salt. Furthermore, the cationic triazolium salts were used to develop a series of unsymmetrical MIC‐triazene‐NHC/MIC' compounds, which can be readily converted to the radical form either by electrochemical or chemical methods. These radicals, which display NIR electrochromism, were investigated using a battery of techniques such as electrochemistry, UV/Vis/NIR and EPR spectroelectrochemistry, and theoretical calculations. Interestingly, the MIC plays an important role in the stabilization of the triazenyl radical, particularly in a competitive role vis‐à‐vis their NHC counterparts. These results shed new light on the ability of MICs to stabilize radicals, and possibly also on their π‐accepting ability. [ABSTRACT FROM AUTHOR]

Previous work has reported the synthesis of donor–acceptor–donor molecules based on dibenzophenazine acceptor group, presenting thermally activated delayed fluorescent (TADF) properties and their application in the assembly of highly efficient electroluminescent devices. Herein, we focus on the characterisation of charge carrier species through UV‐Vis‐NIR spectroelectrochemical and potentiostatic EPR techniques, in addition to the investigation of electropolymerisation properties of some compounds depicted in this study. The promising electrochromic features of both small molecules and conjugated polymers led to the assembly and investigation of electrochromic devices, evidencing the materials' versatility, applied in such different approaches as electrochromic windows and electroluminescent devices. Furthermore, the assembled OLEDs provided high efficiencies, with small roll‐off, EQEs up to 20.5 % and luminance values up to 85 000 cd/m2. [ABSTRACT FROM AUTHOR]

A series of novel osmaindenes 1–6 bearing different substituents (CF3, H, I, Br, OCH3, N(Ph)2) has been synthesized by nucleophilic reaction of water with the corresponding aromatic osmanaphthalyne complexes. All osmaindenes 1–6 have been characterized by elemental analysis (EA) and nuclear magnetic resonance (NMR) spectroscopy, although the low solubilities of 3 and 4 precluded the accumulation of their 13C NMR spectra. Osmaindenes 2, 3 and 5 have also been characterized by single‐crystal X‐ray diffraction analysis. Subsequently, through solid‐state fluorescence spectroscopy, mechanochromic studies, and powder X‐ray diffraction (XRD) analysis, we found that osmaindenes 1–6 fluoresce at wavelengths in the range 500–800 nm, while also displaying reversible mechanochromic properties. The solid‐state fluorescence emission of 1 after grinding extends into the near‐infrared region. This research provides new insight into the design and synthesis of metallic materials with excellent mechanochromic properties. [ABSTRACT FROM AUTHOR]

Asymmetric platinum donor–acceptor complexes [(pimp)Pt(Q2−)] are presented in this work, in which pimp=[(2,4,6‐trimethylphenylimino)methyl]pyridine and Q2−=catecholate‐type donor ligands. The properties of the complexes are evaluated as a function of the donor ligands, and correlations are drawn among electrochemical, optical, and theoretical data. Special focus has been put on the spectroelectrochemical investigation of the complexes featuring sulfonyl‐substituted phenylendiamide ligands, which show redox‐induced linkage isomerism upon oxidation. Time‐dependent density functional theory (TD‐DFT) as well as electron flux density analysis have been employed to rationalize the optical spectra of the complexes and their reactivity. Compound 1 ([(pimp)Pt(Q2−)] with Q2−=3,5‐di‐tert‐butylcatecholate) was shown to be an efficient photosensitizer for molecular oxygen and was subsequently employed in photochemical cross‐dehydrogenative coupling (CDC) reactions. The results thus display new avenues for donor–acceptor systems, including their role as photocatalysts for organic transformations, and the possibility to introduce redox‐induced linkage isomerism in these compounds through the use of sulfonamide substituents on the donor ligands. [ABSTRACT FROM AUTHOR]

Molecular organic radicals have been intensively studied in the last decades, due to their interesting optical, magnetic and redox properties. Here we report the synthesis and characterisation of persistent organic radicals from one‐electron oxidation of redox‐active azines (RAAs), composed of two guanidinyl or related groups. By connecting two different groups together, asymmetric compounds result. In this way a series of compounds with varying redox potential is obtained that could be oxidised reversibly to the mono‐ and the dicationic charge states. The accessible redox states were fully determined by chemical redox reactions. The standard Gibbs free energy change for disproportionation of the radical monocation into the dication and the neutral molecule in solution, estimated from cyclovoltammetric measurements, varies between 43 and 71 kJ mol−1. While the neutral RAAs absorb predominately UV light, the radical monocations display strong absorptions covering almost the entire visible region and extending for some compounds into the NIR region. A detailed analysis of this highly reversible electrochromism is presented, and the fast switching characteristics are demonstrated in an electrochromic test device. [ABSTRACT FROM AUTHOR]

The main obstacle to the widespread application of porphycenes lies in the lack of efficient and economical methods for their production. Discovery of new synthetic methodologies for porphycene derivatives are important for fine‐tuning of their optical and electrochemical properties. Herein, the preparation of a set of AABB‐, ABAB‐, and ABBA‐type meso‐tetrasubstituted unsymmetric porphycenes is reported. Their synthesis involved the acid‐catalyzed oxidative coupling of AA‐ and BB‐dipyrroethenes, or AB‐type dipyrroethenes, as precursors in yields of up to 19 %. The structures were unambiguously confirmed by X‐ray crystallography. The type and position of substituents in the unsymmetric porphycenes enabled fine‐tuning of the optical and electronic properties, which are discussed in terms of their UV/Vis absorption, fluorescence spectroscopies, cyclic voltammetry, and density functional theory calculations. [ABSTRACT FROM AUTHOR]

A series of 'turn-on' fluorescence diarylethenes derived from 2,3-bis(2-methylbenzo[ b]thiophen-3-yl)-5,6-dihydro-4 H-thieno[2,3- b]thiopyran-4-one ( 1) with alkyl and acetyl substituents were synthesized. The photochemical and photophysical properties of these derivatives, including the photoreaction of crystalline 1, were thoroughly investigated to reveal substituent effects on their properties. The results indicated that alkyl substituents did not significantly affect the absorption and emission spectra of the diarylethenes. However, large absorption and emission wavelength shifts were observed for the diarylethene with an acetyl substituent due to extension of π-π conjugation. Significantly, all of the fluorescent ring-closed forms of the compounds isomerized to their ring-open forms in the presence of Cu2+ in the dark. EPR results provide clear evidence for the formation of the compound 1 radical cation intermediate that might be generated in the reaction between c- 1 and Cu2+. DFT calculations found that the ground-state activation energy for ring-opening of 1.+ was approximately 9.2 kcal mol−1 lower than that of 1 without Cu2+, such that a Cu2+-catalyzed oxidative cycloreversion reaction at room temperature might be possible. [ABSTRACT FROM AUTHOR]

Ordered mesoporous alumina-doped titania thin films with anatase crystalline structure were prepared by using triblock copolymer Pluronic P123 as structure-directing agent. Uniform Al doping was realized by using aluminum isopropoxide as a dopant source which can be hydrolyzed together with titanium tetraisopropoxide. Aluminum doping into the titania framework can prevent rapid crystallization to the anatase phase, thereby drastically increasing thermal stability. With increasing Al content, the crystallization temperatures tend to increase gradually. Even when the Al content doped into the framework was increased to 15 mol %, a well-ordered mesoporous structure was obtained, and the mesostructural ordering was still maintained after calcination at 550 °C. During the calcination process, large uniaxial shrinkage occurred along the direction perpendicular to the substrate with retention of the horizontal mesoscale periodicity, whereby vertically oriented nanopillars were formed in the film. The resulting vertical porosity was successfully exploited to fabricate a high-speed and high-quality passive-matrix electrochromic display by using a leuco dye. The vertical nanospace in the films can effectively prevent drifting of the leuco dye. [ABSTRACT FROM AUTHOR]

A new blue chromophore for electrochromic devices: Electrochromism is an intriguing feature that describes the reversible switching between two or more colored states upon oxidation or reduction. Especially the switching from colored to colorless states is an attractive property for application in windows and glasses. In this work, a new intensely blue thiaazulenic quinone (TAQ) and its switching to a colorless anionic state is described. This study sheds light on the electronic processes upon electron injection. Prototypes of electrochromic devices show a high coloration efficiency and complete reversibility after multiple switching cycles. More information can be found in the Communication by U. H. F. Bunz et al. on page 5412. [ABSTRACT FROM AUTHOR]