Aggregation-Induced Emission of Contorted Polycondensed Aromatic Hydrocarbons Made by Edge Extension Using a Palladium-Catalyzed Cyclopentannulation Reaction

Promising CO2 Capture and Effective Iodine Adsorption of Hyper-Cross-Linked Conjugated Porous Organic Polymers Prepared from a Cyclopentannulation Reaction

Three novel conjugated porous organic polymers, denoted as C-POP1-3 and which consist of alternating pyrene cores with various contorted fluorene surrogates, were successfully synthesized from a versatile one-pot palladium-catalyzed [3+2] cyclocondensation reaction. The resulting polymers were obtained in excellent yields and displayed weight-average molecular weights (Mw) ranging from 12.2 to 20.2 kg/mol with polydispersity indices (Mw/Mn) ranging between 1.8 and 2.4, suggesting that the molecular masses are narrowly distributed and thus implying homogeneous polymer chains. Thermal stability exploration of C-POP1-3 by thermogravimetric analysis (TGA) revealed an impressive robustness with a 10% weight reduction temperature attaining 485 °C. Investigation of the inherent microporosity properties of C-POP1-3 via nitrogen adsorption experiments using Brunauer-Emmett-Teller (BET) theory discloses their surface areas which reach up to 560 m2 g-1 and pore volumes averaging 0.47 cm3 g-1. The target conjugated polymers were explored as adsorbents disclosing a maximum carbon dioxide adsorption of 83.0 mg g-1 at 273 K and low pressure for C-POP1, whereas iodine sorption tests portrayed prominent outcomes, notably for C-POP3 which proved to owe a strong affinity toward the hitherto mentioned halogen by achieving a maximum adsorption of 2220 mg g-1. Additionally, recyclability experiments confirmed the possibility to regenerate the polymers' adsorption capabilities even after seven consecutive cycles of adsorption-desorption cycles, which qualify them as auspicious iodine adsorbents.

Tetrahedraphene: A Csp3 -centered 3D Molecular Nanographene Showing Aggregation-Induced Emission

The bottom-up synthesis of 3D tetrakis(hexa-peri-hexabenzocoronenyl)methane, "tetrahedraphene", is reported. This molecular nanographene constituted by four hexa-peri-hexabenzocoronene (HBC) units attached to a central sp3 carbon atom, shows a highly symmetric arrangement of the HBC units disposed in the apex of a tetrahedron. The X-ray crystal structure reveals a tetrahedral symmetry of the molecule and the packing in the crystal is achieved mostly by CH⋅⋅⋅π interactions since the interstitial solvent molecules prevent the π⋅⋅⋅π interactions. In solution, tetrahedraphene shows the same electrochemical and photophysical properties as the hexa-t Bu-substituted HBC (t Bu-HBC) molecule. However, upon water addition, it undergoes a fluorescence change in solution and in the precipitated solid, showing an aggregation induced emission (AIE) process, probably derived from the restriction in the rotation and/or vibration of the HBCs. Time-Dependent Density Functional Theory (TDDFT) calculations reveal that upon aggregation, the high energy region of the emission band decreases in intensity, whereas the intensity of the red edge emission signal increases and presents a smoother decay, compared to the non-aggregated molecule. All in all, the excellent correlation between our simulations and the experimental findings allows explaining the colour change observed in the different solutions upon increasing the water fraction.

Efficient Iodine Uptake of Ultra Thermally Stable Conjugated Copolymers Bearing Biaceanthrylenyl Moieties and Contorted Aromatic Units Using a [3 + 2] Palladium-Catalyzed Cyclopolymerization Reaction

A novel series of copolymers made from alternating aromatic surrogates with contorted and spiro compounds, denoted as BCP1-3, was successfully synthesized employing a palladium-catalyzed one-pot [3 + 2] cyclopentannulation reaction. The resulting copolymers BCP1-3, which were isolated in high yields, exhibited weight-average molecular weights (Mw) ranging from 11.0 to 61.5 kg mol-1 (kDa) and polydispersity index (Mw/Mn) values in the range of 1.7 and 2.0, which suggest a narrow molecular weight distribution, thus indicating the formation of uniform copolymer chains. Investigation of the thermal properties of BCP1-3 by thermogravimetric analysis disclosed outstanding stability with 10% weight loss temperature values reaching 800 °C. Iodine adsorption tests revealed remarkable results, particularly for BCP2, which demonstrated a strong affinity toward iodine reaching an uptake of 2900 mg g-1. Additionally, recyclability tests showcased the effective regeneration of BCP2 after several successive iodine adsorption-desorption cycles.

Dibenzannulated peri-acenoacenes from anthanthrene derivatives

A series of dibenzannulated phenyl-annulated [4,2]peri-acenoacenes have been synthesized in three straightforward steps from 4,10-dibromoanthanthrone (vat orange 3). The phenyl bisannulation of [4,2]peri-acenoacene provides extra stability by increasing the overall aromatic character of the molecules, and allows for a 45-80% increase of the molar extinction coefficient (ε) compared to their [5,2]peri-acenoacene isomers. Depending on the substituents attached to the π-conjugated core, some derivatives exhibit strong aggregation in the solid state with association constant (Ka) up to 255 M-1, resulting in a significant broadening of the absorption spectrum and a substantial decrease of the bandgap value (more than 0.3 V) from solution to the solid state. One [4,2]peri-acenoacene derivative was doubly reduced using cesium and the crystal structure of the resulting salt has been obtained. Field-effect transistors showing a temperature-dependent hole mobility have been tested.

Efficient Removal of Carcinogenic Azo Dyes from Water Using Iron(II) Clathrochelate Derived Metalorganic Copolymers Made from a Copper-Catalyzed [4 + 2] Cyclobenzannulation Reaction

A novel synthetic strategy is disclosed to prepare a new class of metalorganic copolymers that contain iron(II) clathrochelate building blocks by employing a mild and cost-effective copper-catalyzed [4 + 2] cyclobenzannulation reaction, using three specially designed diethynyl iron(II) clathrochelate synthons. The target copolymers CBP1-3 were isolated in high purity and excellent yields as proven by their structural and photophysical characterization, namely, Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and UV-VIS absorption and emission spectroscopies. The thermogravimetric analysis (TGA) of CBP1-3 revealed an excellent chemical stability. Investigation of the adsorption properties of the target copolymers towards the carcinogenic methyl red dye from aqueous solution revealed a quantitative uptake in 30 min. Isothermal adsorption studies disclosed that methyl red uptake from aqueous solution followed the Langmuir model for all of the target copolymers, reaching a maximum adsorption capacity (q_m) of 431 mg g^-. Kinetic investigation revealed that the adsorption followed pseudo-first-order with an equilibrium adsorption capacity (q_e,cal) of 79.35 mg g^- and whose sorption property was sustained even after its reuse several times.

High Uptake of the Carcinogenic Pararosaniline Hydrochloride Dye from Water Using Carbazole-Containing Conjugated Copolymers Synthesized from a One-Pot Cyclopentannulation Reaction

Three conjugated copolymers CAP1-3 were synthesized in one-step via a typical [3+2] cyclopentannulation reaction using a specially designed diethynyl carbazole synthon with various dibrominated polycondensed aromatic hydrocarbons (PAHs). The desired copolymers CAP1-3 were obtained in excellent yields, and their structures were confirmed by ¹H- and ¹³C- nuclear magnetic spectroscopy (NMR), whereas gel permeation chromatography revealed weight-average molar masses (M_w) up to 19.9 kDa with a polydispersity index (PDI) in the range of 2.2-2.6. Interestingly, CAP1-3 exhibits an outstanding capacity to adsorb the carcinogenic pararosaniline hydrochloride dye (Basic Red 9, BR9) from aqueous solutions. Isothermal adsorption studies were carried out following the linear models of Langmuir and Freundlich, divulging an adsorption capacity maximum (q_m) toward BR9 of 483.09 mg g^-1. Investigation of the dye uptake mechanism on CAP1-3 revealed a pseudo-second-order kinetic model for the target copolymer that showed the highest uptake capacity. Recyclability tests disclosed an excellent adsorption efficiency of BR 9 reaching 93% after six cycles.