Does the dehydrogenative coupling of aromatic compounds mediated by AlCl3 at high temperatures and also FeCl3, MoCl5, PIFA, or K3[Fe(CN)6] room temperature proceed same mechanism in all cases? With growing importance synthesis double C-H activation to give various biaryl structures, this question becomes pressing. Since some these reactions only presence non-oxidizing Lewis acids certain oxidants, authors venture hypothesis that, depending on electronic structure substrates nature...

Abstract Läuft die durch AlCl 3 bei hoher Temperatur und auch FeCl , MoCl 5 PIFA oder K [Fe(CN) 6 ] Raumtemperatur vermittelte, dehydrierende Kupplung aromatischer Verbindungen in allen Fällen nach dem gleichen Mechanismus ab? Durch wachsende Bedeutung der Synthese doppelte C‐H‐Aktivierung, zu unterschiedlichen Biarylen führt, wird diese Frage dringlicher. Da einige dieser Reaktionen nur Gegenwart nichtoxidierender Lewis‐Säuren ablaufen andere bestimmter Oxidationsmittel, wagen Autoren...

A diverse set of imidazole- and π-expanded imidazole derivatives displaying excited state intramolecular proton transfer (ESIPT) was designed synthesized. The effect structural variation on photophysical properties studied in detail for nine dyes. relationship between the structure thoroughly elucidated also by comparing with analogues blocked ESIPT functionality. All but one obtained compounds exhibit ESIPT, as demonstrated large Stokes shifts (6500–15 600 cm−1). type π-expansion strongly...

Photoinduced intramolecular direct arylation allows structurally unique compounds containing phenanthro[9',10':4,5]imidazo[1,2-f]phenanthridine and imidazo[1,2-f]phenanthridine skeletons, which mediate excited-state proton transfer (ESIPT), to be efficiently synthesized. The developed polycyclic aromatics demonstrate that the combination of five-membered ring structures with a rigid arrangement between donor acceptor provides means for attaining large fluorescence quantum yields, exceeding...

Suppressing the charge recombination (CR) that follows an efficient separation (CS) is of key importance for energy, electronics, and photonics applications. We focus on role dynamic gating impeding CR in a molecular rotor, comprising electron donor acceptor directly linked via single bond. The media viscosity has unusual dual effect dynamics CS this dyad. For solvents with intermediate viscosity, 1.5-3 times slower than CS. Lowering below ∼0.6 mPa s or increasing it above ∼10 makes 10-30...

The enol–keto excited state dynamics of a series emission tunable imidazole derivatives undergoing intramolecular proton transfer (ESIPT) were determined by means steady and time-resolved spectroscopic techniques in different solvents at room temperature 77 K. Examination the corresponding non-ESIPT compounds, with function deliberately blocked, was carried out for comparison. At temperature, ESIPT process examined samples, picosecond streak camera experiments, had lifetimes ranging from...

Red-emissive π-expanded diketopyrrolopyrroles (DPPs) with fluorescence reaching λ=750 nm can be easily synthesized by a three-step strategy involving the preparation of diketopyrrolopyrrole followed N-arylation and subsequent intramolecular palladium-catalyzed direct arylation. Comprehensive spectroscopic assays combined first-principles calculations corroborated that both N-arylated fused DPPs reach locally excited (S1 ) state after excitation, internal conversion to states solvent...

When the nitro group is located at a distant position with respect to lactam moiety, expanded DPP exhibits strong emission optical brightness exceeding 110 000 (M −1 cm ) in non-polar solvents.

We discovered that phenanthro[9,10-d]imidazoles bearing a 2-halogenoaryl substituent at position 2 undergo swift photochemically driven direct arylation, leading to barely known phenanthro[9',10':4,5]imidazo[1,2-f]phenanthridines. The reaction is high-yielding, and it does not require any sensitizer or base. process tolerant of variety substituents present both positions 1 2; i.e., strongly electron-donating electron-withdrawing are tolerated as well various heterocyclic units. Steric...

Six imidazole derivatives characterized by the presence in their molecules of a sulphonamido group and able to display excited state intramolecular proton transfer (ESIPT) have been synthesized straightforward manner dynamics states investigated detail solvents different polarity proticity: toluene (TOL), dichloromethane (DCM) methanol (MeOH). With exception one compound, these ESIPT-capable are highly luminescent. The major emitting species at room temperature is ketimine (K) tautomer but...

A convenient, general procedure for formylation of diverse range phenols with the Duff protocol has been developed. The gives dialdehydes when possible.

Calix[4]pyrroles bearing two proximally crossing straps on the same or opposite sides have been synthesized for first time. The doubly cis-strapped compound exhibited highly cooperative six-point hydrogen bonding interactions with anion involving both pyrrolic N–Hs and Ar–Hs.

A new methodology for the double N-arylation of diketopyrrolopyrroles with aryl triflates has been developed. It is now possible to prepare bearing N-substituents derived from naphthalene, anthracene and coumarin in two steps commercially available phenols. This represents first time arenes lacking strong electron-withdrawing groups were inserted onto lactamic nitrogen atoms via arylation. The ability incorporate heretofore unprecedented substituents translates increased modulation resulting...

The outcome of the reaction tetracyanoethylene with 1,4-dihydropyrrolo[3,2-b]pyrroles (DHPPs) strongly depends on character substituents present at positions 2 and 5. With electron-withdrawing substituents, does not occur all, while, in contrast, presence electron-donating yields addition–elimination products. When thiazol-2-yl are located 5, addition occurs thiazole ring, rather than DHPP core. In cases where very electron-rich heterocycles a second followed by aromatization, leading to...

A short and efficient access to phenanthro[9,10-d]imidazoles, imidazo[1,2-f]phenanthridines, phenanthro[9′,10′:4,5]imidazo[1,2-f]phenanthridines was achieved by the action of [bis(trifluoroacetoxy)iodo]benzene (PIFA) on properly substituted tetraaryl­-imidazoles. By pre-installing suitable electron-donating groups, it is possible control site intramolecular oxidative aromatic coupling. In particular, placing 3,4-dimethoxyphenyl 3-methoxyphenyl moieties in close proximity, direct reaction...

Abstract “Biomimetic” and “bioinspired” define different aspects of the impacts that biology exerts on science engineering. Biomimicking improves understanding how living systems work, builds tools for bioinspired endeavors. Biological inspiration takes ideas from implements them in unorthodox manners, exceeding what nature offers. Molecular electrets, i.e. with ordered electric dipoles, are key advancing charge-transfer (CT) Protein helices their biomimetic analogues, based synthetic...

Abstract Red‐emissive π‐expanded diketopyrrolopyrroles (DPPs) with fluorescence reaching λ=750 nm can be easily synthesized by a three‐step strategy involving the preparation of diketopyrrolopyrrole followed N‐arylation and subsequent intramolecular palladium‐catalyzed direct arylation. Comprehensive spectroscopic assays combined first‐principles calculations corroborated that both N‐arylated fused DPPs reach locally excited (S 1 ) state after excitation, internal conversion to states...

Abstract π‐Expanded imidazoles bearing the 2‐iodophenyl substituent at position 2 undergo direct photoinduced intramolecular arylation in solid, crystalline state leading to large non‐planar heterocycles. An analogous reaction employing 2‐bromophenyl and 2‐chlorophenyl substituents is considerably slower. Such processes have never before been demonstrated occur crystals allowed efficient synthesizes of structurally unique compounds containing either phenanthro[9′,10′:4,5]imidazo[1,2‐ f...

Two complex π-expanded diketopyrrolopyrroles (EDPPs) have been prepared following multistep but straightforward strategy. We discovered that the fate of these molecules in excited state can be controlled by subtle differences their structure. When NO2 groups are located at a distant position, quadrupolar, centrosymmetric dye possesses strong red emission across solvents’ polarity scale. However, when adjacent to lactam moiety, EDPP has negligible even non-polar solvents. Density Functional...

Abstract The formylation process is carried out by condensation with hexamethylene tetramine (I) followed acidic hydrolysis.

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