Helical Disubstituted Polyacetylenes: Synthesis and Chiroptical Properties of Poly(phenylpropiolate)s

Disubstituted polyacetylenes with helical chirality have been rarely prepared due to the involved synthetic difficulty, and we here report a facile polymerization system for the synthesis of such polymers. Two groups of chiral acetylenes, i.e., C6H5C⋮CCO2R* {R* = [(1S)-endo]-(-)-borneyl (1), (1R,2S,5R)-(-)-menthyl (5), cholesteryl (6)} and C6H5C⋮CCO2C6H4CO2R* [R* = borneyl (2), menthyl (3), cholesteryl (4)], are prepared by esterifications of phenylpropiolic acids with borneol, menthol, and cholesterol. Polymerizations of 1−4 are effected by WCl6−Ph4Sn, giving poly(phenylpropiolate)s P1−P4 with high molecular weights in moderate yields. The structures and properties of the polymers are characterized and evaluated by IR, UV, NMR, CD, TGA, and SEM analyses. All the polymers are stable:  neither decreases in their molecular weights nor changes in their spectra are detected after the polymers have been stored on shelf for ∼3 years, and no weight losses are recorded when the polymers are heated to ∼300 °C. Although the polymers do not possess regioregular Z or E conformations, the polyacetylene backbones are induced to helically rotate by the chiral pendants, as verified by the strong Cotton effects in the backbone absorption region of the polymers (molar ellipticity up to 102 300 deg cm2 dmol-1). The polymers exhibit helical thermochromism, with their chain helicity being continuously and reversibly tunable by temperature change. The helical polymers are capable of self-assembling, as demonstrated by the formation of twisted ribbons upon diffusing a THF solution of P3 into hexane

A Photoinitiator-Grafted Photoresist for Direct In Situ Lithography of Perovskite Quantum Dots

Precise pixel control of quantum dots (QDs) offers unparalleled opportunities for various display applications, such as the OLED and Micro-LED. However, precise selective patterning of QDs is still a challenge due to the lack of a design methodology. Therefore, the aim of this study was thus to develop a photoinitiator-grafted oligomer for “on demand” control of active free radicals to improve the line edge roughness in QD patterning. This photosensitive oligomer was constructed by grafting the photosensitive benzophenone structure onto a phenolic resin oligomer, thus resulting in the confinement of active free radicals and highly selective photolithography. As a proof of concept, we have demonstrated high-quality QD patterns with high resolution and low edge roughness by using direct in situ photolithography. This work opens an avenue for the precise design and synthesis of QD photoresists, improving the precision of QD patterning for display applications

1,4-Selective Polymerization of 1,3-Cyclohexadiene and Copolymerization with Styrene by Cationic Half-Sandwich Fluorenyl Rare Earth Metal Alkyl Catalysts

The regioselective coordination–insertion polymerization of 1,3-cyclohexadiene (CHD) and copolymerization with styrene (S) could be achieved by cationic half-sandwich fluorenyl rare earth metal alkyl catalysts generated by treating half-sandwich fluorenyl rare earth metal dialkyl complexes Flu′Ln­(CH₂SiMe₃)₂(THF)_n (<b>1</b>–<b>10</b>) with an activator (such as [Ph₃C]­[B­(C₆F₅)₄] (<b>A</b>), [PhNHMe₂]­[B­(C₆F₅)₄] (<b>B</b>), or B­(C₆F₅)₃ (<b>C</b>)) and Al^<i>i</i>Bu₃. The homopolymerization of CHD afforded poly­(CHD)­s with complete 1,4 selectivity (1,4 selectivity up to 100%). The copolymerization of CHD with styrene gave new random CHD–S copolymers with CHD content ranging from 22 to 74 mol % containing 1,4-linked CHD–CHD, alternating CHD–S, and syndiotactic S–S sequences unavailable previously. The activity of the copolymerization and the comonomer compositions and sequences of the resulting CHD–S copolymers could be easily controlled by changing the substituted fluorenyl ligand, the metal center, the activator, the temperature, and the molar ratio of comonomers. The residual C–C double bonds of the random CHD–S copolymers could be further epoxidized by <i>meta</i>-chloroperoxybenzoic acid (<i>m</i>CPBA) at room temperature to prepare high-performance polymers with polar groups and reactive sites in the polymer backbone. Such functionalization could improve the solubility, dying, acidity, and surfactivity of these copolymer materials

Synthesis of Polyquinolines via One-Pot Polymerization of Alkyne, Aldehyde, and Aniline under Metal-Free Catalysis and Their Properties

A novel synthetic route to polyquinolines with 6-substituted quinoline as the structural unit was developed based on the polymerization of alkyne–aldehyde monomers and aniline derivatives under the catalysis of Lewis acid B­(C₆F₅)₃. The polymerization was conducted in dichloroethane at 100 °C for 36 h under air atmosphere, affording polyquinolines with molecular weights up to 13 100 and good solubility in most organic solvents. The substituents in aniline exhibited significant effects on the molecular weight, yield, and solubility of the produced polyquinolines. The structures of prepared polymers were characterized and confirmed by GPC, NMR, and FT-IR. The thermogravimetry (TGA) and differential scanning calorimetry (DSC) analysis suggests that the polyquinolines are highly thermal stable. Further photoluminescence behaviors of the prepared polyquinolines were investigated. Based on the characterization results and small molecule reaction mechanism, the polymerization pathway of the polyquinolines was proposed. Our work has provided a novel simple strategy for the preparation of multifunctional polyquinolines with unique architectures by one-pot synthesis under metal-free catalysis

Spontaneous Multicomponent Polymerization of Imidazole, Diacetylenic Esters, and Diisocyanates for the Preparation of Poly(β-aminoacrylate)s with Cluster-Induced Emission Characteristics

Multicomponent polymerization (MCP) is an efficient and rapid method for obtaining multifunctional polymeric materials that have been widely developed in recent years. In this work, poly­(β-aminoacrylate)­s were obtained by spontaneous MCP with the assistance of the C2-amidation of 1-methylimidazole together with diacetylenic esters and diisocyanates. This process can be carried out under mild conditions, such as in a catalyst-free and room-temperature environment. Through the systematic optimization of the polymerization conditions, the resultant poly­(β-aminoacrylate)­s could have molecular weights of up to 24 100 g/mol and excellent yields (up to 94%). All the polymers were well-characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), and Fourier transform infrared spectroscopy (FT-IR), and all the collected data illustrated that the polymerization mechanism corresponds to a model reaction of small molecules. The photophysical property of these obtained polymers indicated that one of the polymers (polymer P1b2a) demonstrated a luminescence capability that was unconventional because no fluorescent emitters were present in its main chains or side chains. A further study suggested that the clustering of diverse subgroups with subsequent electron cloud overlapping, which resulted in molecular conformation rigidification, was primarily responsible for this emission. Thus, the current MCP method will provide guidance for preparing new nonconjugated polymers with cluster-induced emissive functional materials for easily tailored specific applications

From Nonconjugated Diynes to Conjugated Polyenes: Syntheses of Poly(1-phenyl-7-aryl-1,6-heptadiyne)s by Cyclopolymerizations of Asymmetrically α,ω-Disubstituted Alkadiynes

From Nonconjugated Diynes to Conjugated Polyenes:  Syntheses of Poly(1-phenyl-7-aryl-1,6-heptadiyne)s by Cyclopolymerizations of Asymmetrically α,ω-Disubstituted Alkadiyne

Syntheses, Hydrogen-Bonding Interactions, Tunable Chain Helicities, and Cooperative Supramolecular Associations and Dissociations of Poly(Phenylacetylene)s Bearing l-Valine Pendants: Toward the Development of Proteomimetic Polyenes^†

4-Ethynylbenzoyl-l-valine methyl ester (1e), an acetylene−valine adduct, is polymerized by organorhodium catalysts to the corresponding “polyester” (P1e) of high molecular weights (Mw up to 371 000) and high stereoregularities (Z content up to 100%) in high yields (up to ∼95%). The amino acid residues form intrastrand and interstrand hydrogen bonds within and between the polymer chains. The ester groups of P1e are selectively deprotected by base-catalyzed hydrolysis, giving “polyacid” P1a with “free” valine pendants. While 1e is CD-inactive at λ > 300 nm, both P1e and P1a exhibit intense Cotton effects in the long wavelength region where the polyacetylene backbone absorbs, confirming that the chiral valine pendants have induced the polymer chain to take a helical conformation with an excess in one handedness. The helicity of the chain segments is sensitive to the variations in their environmental surroundings. Utilizing this environmental susceptibility, the chain helicity of the polymers is tuned continuously by such external stimuli as solvent, temperature, pH, and additive, with cooperativity being observed in most systems. The manipulation of the chain helicity by solvent and pH is fully reversible

1,4-Selective Polymerization of 1,3-Cyclohexadiene and Copolymerization with Styrene by Cationic Half-Sandwich Fluorenyl Rare Earth Metal Alkyl Catalysts

The regioselective coordination–insertion polymerization of 1,3-cyclohexadiene (CHD) and copolymerization with styrene (S) could be achieved by cationic half-sandwich fluorenyl rare earth metal alkyl catalysts generated by treating half-sandwich fluorenyl rare earth metal dialkyl complexes Flu′Ln­(CH₂SiMe₃)₂(THF)_n (<b>1</b>–<b>10</b>) with an activator (such as [Ph₃C]­[B­(C₆F₅)₄] (<b>A</b>), [PhNHMe₂]­[B­(C₆F₅)₄] (<b>B</b>), or B­(C₆F₅)₃ (<b>C</b>)) and Al^<i>i</i>Bu₃. The homopolymerization of CHD afforded poly­(CHD)­s with complete 1,4 selectivity (1,4 selectivity up to 100%). The copolymerization of CHD with styrene gave new random CHD–S copolymers with CHD content ranging from 22 to 74 mol % containing 1,4-linked CHD–CHD, alternating CHD–S, and syndiotactic S–S sequences unavailable previously. The activity of the copolymerization and the comonomer compositions and sequences of the resulting CHD–S copolymers could be easily controlled by changing the substituted fluorenyl ligand, the metal center, the activator, the temperature, and the molar ratio of comonomers. The residual C–C double bonds of the random CHD–S copolymers could be further epoxidized by <i>meta</i>-chloroperoxybenzoic acid (<i>m</i>CPBA) at room temperature to prepare high-performance polymers with polar groups and reactive sites in the polymer backbone. Such functionalization could improve the solubility, dying, acidity, and surfactivity of these copolymer materials

Fabrication, Electrochemical, and Optoelectronic Properties of Layer-by-Layer Films Based on (Phthalocyaninato)ruthenium(II) and Triruthenium Dodecacarbonyl Bridged by 4,4′-Bipyridine as Ligand

4-(2-(4-Pyridinyl)ethynyl)benzenic diazonium salt (PBD) was synthesized and used to modify the substrate by self-assembly (SA) technique. Following decomposition of the diazonium group in PBD under UV irradiation, the ionic bonds between the diazonium salt and substrate are converted to covalent bonds. The PBD monolayer film anchored on substrates is very stable. Furthermore, the layer-by-layer (LBL) self-assembled films of bis(4,4′-bipyridine)(phthalocyaninato)ruthenium(II) (RuPc(bipy)2, BPR) and triruthenium dodecacarbonyl (Ru3(CO)12, TRDC) were fabricated on the PBD-modified substrates and characterized using UV−vis absorption spectroscopy, atomic force microscopy (AFM), and electrochemistry. The UV−vis analysis results indicate that the LBL TRDC-BPR self-assembled multilayer films with axial ligands between ruthenium atoms and pyridine groups were successfully fabricated and the progressive assembly runs regularly with almost equal amounts of deposition in each cycle. The AFM images of the seven-bilayer TRDC-BPR film on silicon wafer showed round-shaped small domains with sizes of 30−40 nm. The values of the energy band gap (Eg), the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) of six-bilayer TRDC-BPR on indium-tin-oxide (ITO) glass slides were measured using the UV−vis absorption spectrum and a cyclic voltammogram with values of 1.8, −5.0, and −3.2 eV, respectively. Under illumination, the self-assembled film on ITO showed effective photoinduced charge transfer and changed the current density. As the number of bilayers was increased, the photocurrent increased and reached its maximum value (∼150 nA/cm2) at six bilayers. A further increase in the number of bilayers led to a decrease in current due to the increase in cell resistance. The results allow us to design new materials with higher performance for optoelectronic applications