Carlos

The cocrystallization of a weakly luminescent platinum complex [Pt(btpy)(PPh₃)Cl] (1) (Hbtpy=2-(2benzothienyl)pyridine; emission quantum yield Φ_em=0.03) with fluorinated bromo- and iodoarenes C₆F_6-nX_n (X=Br, I; n=1, 2) results in the formation of efficient halogen-bonding (XB) interactions PtCl⋅⋅⋅XR. An up to 22-fold enhancement (Φ_em=0.65) in the luminescence intensity of the cocrystallized compound is detected, without a substantial change of the emission energy. Based on crystallographic, photophysical, and theoretical investigations, the contribution of the XB donors C₆F_6-nX_n to the amplification of luminescence intensity is attributed to the enhancement of spin–orbit coupling through the heavy-atom effect, and simultaneously to the suppression of the nonradiative relaxation pathways by increasing the rigidity of the chromophore center.

Hal-lighted: A weakly luminescent Pt complex readily cocrystallizes with fluorinated bromo- and iodoarenes (halogen-bond donors) to form compounds with significantly increased emission quantum yields (Φ_em). The effect is attributed to the combination of enhanced spin–orbit coupling and structural rigidity in the cocrystallized compound that suppresses the nonradiative decay rate.

The development of a one-step borylation of 1,3-diaryloxybenzenes, yielding novel boron-containing polycyclic aromatic compounds, is reported. The resulting boron-containing compounds possess high singlet-triplet excitation energies as a result of localized frontier molecular orbitals induced by boron and oxygen. Using these compounds as a host material, we successfully prepared phosphorescent organic light-emitting diodes exhibiting high efficiency and adequate lifetimes. Moreover, using the present one-step borylation, we succeeded in the synthesis of an efficient, thermally activated delayed fluorescence emitter and boron-fused benzo[6]helicene.

Easy boryl LEDs: A one-step borylation of 1,3-diaryloxybenzenes has been developed. The resulting boron-containing aromatic compounds possess high singlet–triplet excitation energies as a result of localized frontier molecular orbitals induced by boron and oxygen. These compounds are efficient host and emitting materials for organic light-emitting diodes.

Adsorption and desorption play major roles in separations, purification of water, waste streams, liquid fuels, catalysis, biomedicine and chromatography. Mesoporous metal–organic frameworks (MOFs) with pore sizes 2–50 nm are particularly suitable for adsorption of organic compounds in solution. Tens of thousands of aromatic and heterocyclic compounds are major components of liquid fuels, feedstock for industrial synthesis, solvents, dyestuffs, agricultural chemicals, medicinal drugs, food additives, and so forth. This Review provides a systematization and analysis of studies on adsorption/desorption on mesoporous MOFs in solution and their underlying chemical mechanisms. The (in)stability of mesoporous MOFs in water is critically discussed. Adsorption capacity and selectivity are covered for organic dyes, medicinal drugs, major components of liquid fuels, and miscellaneous industrial chemicals. Ionic interactions, Brønsted acid–base interactions, hydrogen bonding, coordination bonding, π–π interactions, and non-specific interactions are covered amongst adsorption mechanisms. The effects of post-synthetic modifications of mesoporous MOFs on their stability, adsorption capacity, selectivity, and mechanisms of adsorption and desorption are analyzed. To encourage research in this quickly growing field, we identify “niches” for which no application-oriented and/or mechanistic studies were reported. Perspectives and limitations of a wide use of mesoporous MOFs as industrial sorbents are discussed.

MOFs as sorbents: Aromatic and heterocyclic compounds are abundantly present in liquid fuels, among industrial chemicals, dyes, drugs, and so forth. This Review analyzes their adsorption/desorption on mesoporous MOFs in solution and associated molecular mechanisms. (In)stability of mesoporous MOFs in water is critically discussed. Perspectives and limitations of using mesoporous MOFs as industrial sorbents are assessed.

Persistent room temperature phosphorescence (RTP) from pure organic luminogens can be rationally realized based on the crystallization-induced phosphorescence phenomenon and severe crystallization. A perfect crystal with dense molecular packing and effective inter­molecular interactions isolates the triplet excitons from quenching sites and significantly blocks the high-energy vibrational dissipation, thus yielding long-lasting RTP.

The detailed synthesis and characterization of four ruthenium(II) complexes [RuLL′(NCS)₂] is reported, in which L represents a 2,2′-bipyridine ligand functionalized at the 4,4′ positions with benzo[1,2-b:4,5-b′]dithiophene derivatives (BDT) and L′ is 2,2′-bipyridine-4,4′-dicarboxylic acid unit (dcbpy) (NCS=isothiocyanate). The reaction conditions were adapted and optimized for the preparation of these amphiphilic complexes with a strong lipophilic character. The photovoltaic performances of these complexes were tested in TiO₂ dye-sensitized solar cell (DSSC) achieving efficiencies in the range of 3–4.5 % under simulated one sun illumination (AM1.5G).

Ru ready for this: Four (cis)tris-heteroleptic complexes based on benzo[1,2-b:4,5-b′]dithiophene are reported. The conditions of synthesis needed to be adapted because of the strong lipophilic character of these amphiphilic molecules (see figure). In particular, the (arene)Ru^II half-sandwich complex intermediates involved in the first reaction step were formed quantitatively, which suggests that the partial scrabbling process must occur during the second step (see figure).

Iminosulfane(phosphane)carbon(0) derivatives (iSPCs; Ar₃PCSPh₂(NMe); Ar=Ph (1), 4-MeOC₆H₄ (2), 4-(Me₂N)C₆H₄ (3)) have been successfully synthesized and the molecular structure of 3 characterized. Carbone 3 is the first thermally and hydrolytically stable carbone stabilized by phosphorus and sulfur ligands. DFT calculations reveal the electronic structures of 1–3, which have two lone pairs of electrons at the carbon center. First and second proton affinity values are theoretically calculated to be in the range of 286.8–301.1 and 189.6–208.3 kcal mol⁻¹, respectively. Cyclic voltammetry measurements reveal that the HOMO energy levels follow the order of 3>2>1 and the HOMO of 3 is at a higher energy than those of bis(chalcogenane)carbon(0) (BChCs). The reactivities of these lone pairs of electrons are demonstrated by the C-diaurated and C-proton-aurated complexes. These results are the first experimental evidence of phosphorus- and sulfur-stabilized carbones behaving as four-electron donors. In addition, the reaction of hydrochloric salts of the carbones with Ag₂O gives the corresponding Ag^I complexes. The resulting silver(I) carbone complexes can be used as carbone transfer agents. This synthetic protocol can also be used for moisture-sensitive carbone species.

Getting tough on carbon: The combination of the high electron-donating ability of the triarylphosphane ligand and the strong π-acceptor ability of the iminosulfane ligand confers considerable thermal and hydrolytic stability on iminosulfane(phosphane)carbon(0) (see figure). The four-electron donor ability of these carbon complexes is revealed by the synthesis of aurated complexes.

A series of pyrene/phenanthrene-fused furan derivatives (1–8) were synthesized by a simple condensation reaction between pyrene-4,5-diketone/phenanthrenequinone and substituted phenol/naphthol in the presence of trifluoromethanesulfonic acid in 1,2-dichlorobenzene heated at reflux. The formed compounds can emit strong blue light in organic solvents. Additionally, the self-assembly behaviors of two of the compounds (3 and 5) were studied through re-precipitation method and the resulting nanostructures were characterized by UV/Vis, fluorescence spectra, and field-emission scanning electron microscopy (FESEM). The findings showed that the shape and size of compounds 3 and 5 could be tuned by the ratio of THF and hexadecyl trimethyl ammonium bromide (CTAB) solution in water.

Fluorescent furan-embedded heteroarenes: Eight enlarged cyclic pyrene/phenanthrene-fused furan derivatives were synthesized through a one-step reaction. All the resulting compounds emitted blue fluorescence in dichloromethane. The self-assembly behaviors of two of the molecules were investigated (see figure), indicating that the shape, size, and morphology could be tuned by the ratio of THF to a solution of hexadecyl trimethyl ammonium bromide (CTAB).

Photolysis of the cyclic phosphine oligomer [PPh]₅ in the presence of pentaarylboroles leads to the formation of 1,2-phosphaborines by the formal insertion of a phenylphosphinidene fragment into the endocyclic CB bond. The solid-state structure features a virtually planar central ring with bond lengths indicating significant delocalization. Appreciable ring current in the 1,2-phosphaborine core, detected in nuclear independent chemical shift (NICS) calculations, are consistent with aromatic character. These products are the first reported 1,2-BPC₄ conjugated heterocycles and open a new avenue for BP as a valence isoelectronic substitute for CC in arene systems.

Jamming PB into benzene: 1,2-Phosphaborines were synthesized by the ring expansion reaction of boroles with the cyclic phosphine [PPh]₅ under UV irradiation. The products were structurally characterized revealing a planar central ring. The nature of the bonding was analyzed computationally and indicated that the heterocycle had appreciable aromatic character.