On-surface chemistry aims to overcome the limitations of conventional in-solution synthesis by taking advantage of the confinement in two dimensions to master highly ordered covalent structures with tailored properties. So far, most of the reported work is conducted on metal substrates and relies on unconventional mechanisms, thereby precluding a direct transposition of well-established organic reactions from solutions to surfaces. In addition, the intrinsic properties and reactivity of metal substrates often limit the activation methods available to trigger on-surface reactions, and photoinduced processes are especially difficult to handle due to quenching of the adsorbed precursor molecules. Herein, the photoinduced deoxygenation of dibenzothiophene S -oxide (DBTO) derivatives is transposed from solutions to insulating alkali halide surfaces in ultra-high vacuum. By combining in-solution and on-surface investigations by means of scanning tunneling microscopy, non-contact atomic force microscopy, as well as bias spectroscopy measurements, we provide evidence of the successful on-surface deoxygenation of individual DBTO derivatives under UV irradiation. The photoinduced deoxygenation is conducted at low temperature (<25 K) on a NaCl thin film formed on a Au(111) substrate to yield the reduced dibenzothiophene (DBT) product with excellent chemoselectivity. This work thus opens the way to in-situ photocontrolled charge state manipulation in purely organic compounds.

The “precursor approach” has proved particularly valuable for the preparation of insoluble and unstable π-conjugated polycyclic compounds (π-CPCs), which cannot be synthesized via in-solution organic chemistry, for their improved processing, as well as for their electronic investigation both at the material and single-molecule scales. This method relies on the synthesis and processing of soluble and stable direct precursors of the target π-CPCs, followed by their final conversion in situ, triggered by thermal activation, photoirradiation or redox control. Beside well-established reactions involving the elimination of carbon-based small molecules, i.e., retro-Diels–Alder and decarbonylation processes, the late-stage extrusion of chalcogen fragments has emerged as a highly promising synthetic tool to access a wider variety of π-conjugated polycyclic structures and thus to expand the potentialities of the “precursor approach” for further improvements of molecular materials’ performances. This review gives an overview of synthetic strategies towards π-CPCs involving the ultimate elimination of chalcogen fragments upon thermal activation, photoirradiation and electron exchange.

During the purification of a reported compound named 1,3-dihydrobenzo[c]thiophene, we isolated an unexpected molecule in one of the chromatography fractions by serendipity. Structural elucidation using common techniques such as 1D and 2D NMR, and mass spectrometry revealed the nature of this novel product characterized as cyclo[tri(thiomethyl-1,2-phenylmethylene)].

The transition metal-catalyzed C-H activation of arenes directed by sulfoxides represents a compelling strategy in organic synthesis, owing to its exceptional regioselectivity and high efficiency. This innovative approach stands out for its traceless character, enabling the direct functionalization of arenes, before the easy removal or conversion of the key sulfinyl moiety. Beyond their utility as a directing group, sulfoxides have proved particularly valuable to mediate as chiral auxiliaries, presenting exciting prospects for the synthesis of stereo-enriched compounds upon C-H functionalization. The versatility demonstrated by the method paves the way to different structures with potential applications ranging from medicinal chemistry to organic electronics.

While hexaphenylsilacyclopentadiene (hexaphenylsilole) is viewed as an archetypal Aggregation-Induced Emission (AIE) luminogen, its isostructural hydrocarbon surrogate hexaphenylcyclopentadiene has strikingly never been investigated in this context, most probably due to a lack of synthetic availability. Herein, we report a straightforward synthesis of hexaphenylcyclopentadiene, via the direct perarylation of cyclopentadiene upon copper(I) catalysis under microwave activation, with the formation of six new C-C bonds in a single synthetic operation. Using zirconocene dichloride as a convenient source of cyclopentadiene and a variety of aryl iodides as coupling partners, this copper-catalyzed cross-coupling reaction gave rise to a series of unprecedented hexaarylcyclopentadienes, displaying promising properties as AIE luminogens. In addition, these propeller-shaped perarylcyclopentadienes are direct precursors of π-extended conjugated polycyclic compounds, and their cyclodehydrogenation under Scholl reaction conditions yielded helicenic 17,17-diarylcyclopenta[l,l’]diphenanthrenes. These structurally complex polyannelated fluorene derivatives can now be prepared in only two synthetic steps from cyclopentadiene for applications as organic semiconductors or fluorophores.

Materials capable of dynamically and reversibly altering their emission are relevant for numerous optical applications. Here, the anisotropic morphology‐directed light emission from fluorescent Janus emulsion droplets, an intrinsically chemo‐responsive material platform, is investigated. Informed by experimental observations of morphology‐dependent optical confinement of internally emitted light within the higher refractive index phases, ray‐tracing is used to predict and fine‐tune the droplets’ optical properties and their ability to concentrate light. Theoretical prediction and closely matching experimental results show that the collection of incident light and the confinement of emitted light in the internal droplet phase due to total internal reflection both contribute to the droplets’ anisotropic light emission profile. A novel ratiometric dual‐angle fluorescence detection approach that exploits the gravitational alignment of the droplets is implemented to quantify the morphology‐dependent large‐scale chemically‐induced modulation of the anisotropic emission of droplet layers. Relevant emulsion design parameters are systematically examined to enhance the signal‐to‐noise ratio, and a second emitter is co‐compartmentalized inside the droplets to amplify the anisotropic light confinement via an absorption–emission cascade. Preferential excitation of dyes in proximity to the internal droplet interface enhances the collected light intensity, demonstrating that dye‐loaded Janus emulsion droplets function as stimuli‐responsive, tunable, fluorescent optical elements.

Stimuli-triggered alterations in biphasic Janus emulsion droplet morphologies enable controllable modulation of the area of surfactant-functionalized liquid–liquid interfaces. This effect can be used to induce aggregation-induced emission from tetraphenylethylene-functionalized surfactants, yielding a novel stimuli-responsive fluorescent material platform. Here, TPE aggregation and emission on an interface are shown in front of a fluorescence micrograph of the actual system. More information can be found in the Research Article by L. Zeininger and co-workers (DOI: 10.1002/chem.202203790).

We report a novel stimuli-responsive fluorescent material platform that relies on an evocation of aggregation-induced emission (AIE) from tetraphenylethylene (TPE)-based surfactants localized at one hemisphere of biphasic micro-scale Janus emulsion droplets. Dynamic alterations in the available interfacial area were evoked through surfactant-induced dynamic changes of the internal droplet morphology that can be modulated as a function of the balance of interfacial tensions of the droplet constituent phases. Thus, by analogy with a Langmuir-Blodgett trough that enables selective concentration of surfactants at a liquid-gas interface, we demonstrate here a method for controllable modulation of the available interfacial area of surfactant-functionalized liquid-liquid interfaces. We show that a morphology-dependent alteration of the interfacial area can be used to evoke an optical signal, by selectively assembling synthesized TPE-based surfactants on the respective droplet interfaces. A trigger-induced increase in the concentration of TPE-based surfactants at the liquid-liquid interfaces results in an evocation of aggregation-induced emission (AIE), inducing an up to 3.9-fold increase in the measured emission intensity of the droplets.

Carbazole and fluorene-substituted benzidine blocks have been functionalized with two different solubilizing pendant groups, in order to enhance the material's solubility in greener solvents. Preserving the optical and electrochemical properties, the aromatic function and substitution showed an important influence on the solvent affinity, achieving concentrations up to 150 mg/mL in o-xylenes for the glycol-containing materials and decent solubility in alcohols for the compounds functionalized with ionic chains. The latter solution proved to be ideal for the preparation of luminescence slot-die coating film on top of flexible-substrates up to 33 cm x 2 cm. As a proof of concept, the materials have been implemented in different organic electronic devices, highlighting the low turn-on voltage (4 V) presented by the OLEDs, which is comparable with vacuum-processed devices. A structure-solubility relationship and a synthetic strategy are disentangled in this manuscript to tailor organic semiconductors and adapt their solubility towards the desired solvent and application.

Herein, series bay position‐substituted N‐annulated perylene diimide (N‐PDI) derivatives applied as the cathode interlayer (CIL) in bottom‐anode (conventional structure) organic solar cells (OSCs) are presented. Despite the fact that N‐PDIs show low solubility in common CIL‐processing solvents such as methanol (MeOH), the use of ethyl acetate (EtOAc) as a processing solvent allows for dissolution of N‐PDIs at sufficient concentrations to form homogeneous films on top of the organic photoactive layer. OSC devices fabricated in ambient conditions using the PM6:Y6 representative bulk heterojunction (BHJ) system show simultaneous enhancements in performance metrics, with power conversion efficiency (PCE) increasing from 8.5% for devices based on the bare Ag cathode to 12.5% with N‐PDI molecule as CIL. The improvement in performance with N‐PDI CILs can be attributed to a combination of smooth film morphology and high electron extraction capability of N‐PDIs. Solubility in EtOAc, appropriate highest occupied molecular orbital/lowest unoccupied molecular orbital energy levels, uniform film formation, and facilitation of electron transfer/collection make these N‐PDIs a promising family of CIL materials for efficient OSCs. Using EtOAc as an improved solvent over MeOH also opens the door for new CIL designs and to test materials that are not MeOH soluble.

Responsive materials capable of autonomously regulating and adapting to molecular recognition‐induced chemical events hold great promise in the design of artificial chemo‐intelligent life‐like soft material platforms. In this context, the design of a synthetically minimal artificial emulsion platform that, regulated by interfacial supramolecular recognition events, is capable to autonomously and reversibly adapt to its chemical environment is reported. The systems exhibit programmed up‐ and down‐regulating capabilities that are realized via selective assembly of synthesized crown ether surfactants onto one hemisphere of anisotropic biphasic emulsion droplets. Dynamic and reversible interfacial host–guest complexation of, for example, metal and ammonium ions or amino acids transduce into interface‐triggered morphological reconfigurations of the complex emulsion droplets, which mediate their ability to selectively present, hide, or expand liquid–liquid interfaces. The separate responsive modalities are then used to showcase the utility of such adaptive soft material platforms for a self‐regulated uptake and release of metal ions or phase‐transfer catalysts, a biomimetic recognition of biomolecules including amino acids, carbohydrates, and antibodies, and for triggered surface‐encoded payload release applications.

Synthesis and use of the unprecedented thiochromenocarbazole imide (TCI) for the preparation of printed, large-area and flexible OLEDs.

Photodynamic therapy is a clinically approved anticancer modality that employs a light-activated agent (photosensitizer) to generate cytotoxic reactive oxygen species (ROS). There is therefore a growing interest for developing innovative photosensitizing agents with enhanced phototherapeutic performances. Herein, we report on a rational design synthetic procedure that converts the ultrabright benzothioxanthene imide ( BTI ) dye into three heavy-atom-free thionated compounds featuring close-to-unit singlet oxygen quantum yields. In contrast to the BTI , these thionated analogs display an almost fully quenched fluorescence emission, in agreement with the formation of highly populated triplet states. Indeed, the sequential thionation on the BTI scaffold induces torsion of its skeleton reducing the singlet-triplet energy gaps and enhancing the spin-orbit coupling. These potential PSs show potent cancer-cell ablation under light irradiation while remaining non-toxic under dark condition owing to a photo-cytotoxic mechanism that we believe simultaneously involves singlet oxygen and superoxide species, which could be both characterized in vitro. Our study demonstrates that this simple site-selected thionated platform is an effective strategy to convert conventional carbonyl-containing fluorophores into phototherapeutic agents for anticancer PDT.

Four D-pi-A push-pull derivatives either based on a diphenylmethylamine or a 9-methylcarbazole electron-rich block (D), connected to a dicyanovinyl accepting moiety (A) through two different spacers (pi), namely a thiophene or selenophene, were synthesized and characterized. These small and synthetically accessible molecules were indeed selected to rationalize the impact of both i) the rigidification of the arylamine part and ii) the nature of the pi-spacer constituting heteroatom on the optical, electrochemical, charge transport and therefore photovoltaic properties.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Direct (hetero)-arylation was used to prepare two push–pull molecules. Optimization of the experimental coupling conditions and their preliminary evaluation as active materials in simple air-processed organic solar cells are reported herein.

Singlet-triplet interconversions (intersystem crossing, ISC) in organic molecules are at the basis of many important processes in cutting-edge photonic applications (organic light-emitting devices, photodynamic therapy, etc.). Selection rules for these transitions are mainly governed by the spin-orbit coupling (SOC) phenomenon. Although the SOC relies on complex relativistic phenomena, theoreticians have, with time, developed increasingly sophisticated and efficient approaches to gain access to a satisfactory evaluation of its magnitude. However, recent works have highlighted the remarkable and somehow unexpected efficiency of dimers of small conjugated molecules in terms of ISC quantum yields, whose origin has not been completely investigated. In this work, we bring a coupled experimental and theoretical analysis of the origin of the unusually large ISC efficiency on a series of such dimers that differ by their nature (covalent or supramolecular). We show that considering the dynamical nature of the SOC, and especially its dependence on angular orientations between the dimer subunits sometimes overlooked in the literature, it is necessary to rationalize some counterintuitive experimental observations. This combined experimental and theoretical work paves the way for new molecular engineering rules for SOC control.

This article reports on the synthesis and first use of a POSS-arylamine based push–pull octamer as molecular donor in organic solar cells.

In organic solar cells, photogenerated singlet excitons form charge transfer (CT) complexes, which subsequently split into free charge carriers. Here, the contributions of excess energy and molecular quadrupole moments to the charge separation process are considered. The charge photogeneration in two separate bulk heterojunction systems consisting of the polymer donor PTB7‐Th and two non‐fullerene acceptors, ITIC and h‐ITIC, is investigated. CT state dissociation in these donor–acceptor systems is monitored by charge density decay dynamics obtained from transient absorption experiments. The electric field dependence of charge carrier generation is studied at different excitation energies by time delayed collection field (TDCF) and sensitive steady‐state photocurrent measurements. Upon excitation below the optical gap, free charge carrier generation becomes less field dependent with increasing photon energy, which challenges the view of charge photogeneration proceeding through energetically lowest CT states. The average distance between electron–hole pairs at the donor–acceptor interface is determined from empirical fits to the TDCF data. The delocalization of CT states is larger in PTB7‐Th:ITIC, the system with larger molecular quadrupole moment, indicating the sizeable effect of the electrostatic potential at the donor–acceptor interface on the dissociation of CT complexes.

The pallado-catalyzed cyanation of benzothioxanthene imide (BTXI) derivatives is explored herein. Once optimized on the monobromo BTXI, mild reaction conditions were successfully applied to the dibromo derivative affording two regioisomers that have been isolated and structurally solved. Additional hydrogen-deuterium exchange experiments were carried out to support a proposed mechanism involving the formation of a five-membered palladacycle intermediate in the bay area. As well as impacting the structural, photo physical and electrochemical properties of the BTXI core, nitrile moieties were successfully used as orthogonal protecting groups, thus opening doors to new design principles.