A new polymerisation route to conjugated polymers : Regio-and stereoselective synthesis of linear and hyperbranched poly ( arylene chlorovinylene ) s by decarbonylative polyaddition of aroyl chlorides and alkynes

We present here a new polymerisation route for the synthesis of new conjugated polymers. Decarbonylative polyadditions of diyne monomers [bis(4-ethynylphenyl)dimethylsilane, 4,4′-diethynylbiphenyl, and 1,2-bis(4-ethynylphenyl)-1,2-diphenylethene] with respective terephthaloyl dichloride and benzene-1,3,5-tricarbonyl trichloride catalyzed by [Rh(cod)Cl]2/PPh3, [Rh(nbd)Cl]2/PPh3, [RhCp*Cl2]2/PPh3, [Rh(cod)(PPh3)2]+PF6−, or [Rh(cod)(PPh2)(CH2)4(PPh2)]+BF4− (cod = 1,5-cyclooctadiene, nbd = 2,5-norbornadiene, Cp* = pentamethyl cyclopentadienyl), proceed smoothly, producing linear and hyperbranched poly(arylene chloroZ-vinylene)s (PACVs) in regio- and stereoselective manners with high molecular weights (absolute Mw up to 5.31 × 105) in high yields (up to 92%). Model reactions are designed to confirm the chemical structures of the PACVs. The resultant polymers are processable and enjoy high thermal stability. The linear PAVCs can undergo thermal curing at high temperatures and compared with their hyperbranched counterparts, they are more electronically conjugated due to the para-conjugation effect, as revealed by both experimental and theoretical studies. The light emissions of linear PAVCs with twisted tetraphenylethene units are enhanced by aggregate formation, demonstrating an unusual aggregation-enhanced emission characteristic.


General information
Toluene and tetrahydrofuran (THF) were distilled in an atmosphere of nitrogen from sodium benzophenone ketyl immediately prior to use.o-Xylene was dried over anhydrous magnesium sulphate.Dichloromethane (DCM) was distilled under nitrogen over calcium hydride.The rhodium complexes [Rh(cod)Cl] 2 , 1 [Rh(nbd)Cl] 2 , 2 and [RhCp*Cl 2 ] 2 , 3 were prepared according to the published procedures.was measured on a Jianke differential refractometer to be 0.244 mL/g in THF at 25 °C.
X-ray diffraction intensity data of the monomer were collected at 173 K on a Bruker-Nonius Smart Apex CCD diffractometer with graphite-monochromated Mo Kα radiation.The data were processed using the SAINT and SADABS routines, and the structure solution and refinement were carried out by the SHELXTL suite of X-ray programs (version 6.10) (Table S1).IR spectra were recorded on a Perkin-Elmer 16 PC FTIR spectrophotometer. 1 H and 13 C NMR spectra were measured on Bruker ARX 300 or 400 NMR spectrometers using chloroform-d as solvent.Optical absorption spectra were measured on a Milton Ray Spectronic 3000 array spectrophotometer.High resolution mass spectra

Monomer synthesis
Monomers 1a 4 and 1b 5 were prepared according to the literatures.Monomer 1c was synthesized according to the synthetic route shown in Scheme S1.

Synthesis of 1,2-bis(4-bromophenyl)-1,2-diphenylethene (Br 2 TPE
). 6 In a two-necked flask equipped with a magnetic stirrer were added 4-bromobenzophenone (5 g, 19.2 mmol), zinc powder (2.5 g, 38.3 mmol), and 60 mL of THF.After the mixture was cooled to -78 °C, TiCl 4 (2.1 mL, 19.2 mmol) was slowly added by a syringe.The mixture was warmed to room temperature and stirred for 0.5 h and then heated to reflux for overnight.After cooled to room temperature, the reaction mixture was quenched with hydrochloric acid aqueous solution and then extracted with DCM.The organic layer was collected and concentrated.The crude product was purified by silica-gel column chromatography to give a white solid in a yield of 90%.

Polymer synthesis
All the polymerisation reactions were carried out under nitrogen using standard Schlenk technique in a vacuum line system or an inert atmosphere glovebox.A typical experimental procedure for the polymerisation of the monomers 1a and 2 using C1 as catalyst is described below.
To a 15 mL Schlenk tube with a three-way stopcock on the sidearm was placed 8.9 mg (0.018 mmol) of C1, 9.5 mg (0.036 mmol) of PPh 3 , 78.1 mg of 1a, and 60.9 mg of 2 under nitrogen in a glovebox.
Freshly dried o-xylene (3 mL) was then injected into the tube using a hypodermic syringe.The resultant mixture was stirred at 140 o C under nitrogen for 12 h.The polymerisation was quenched by the addition of a small amount of methanol.The solution was then added dropwise to 500 mL of hexane via a cotton filter under stirring.The precipitate was allowed to stand overnight and then collected by filtration.The polymer was washed with hexane and dried under vacuum at room temperature to a constant weight.

Model reactions
To confirm the occurrence of the decarbonylative polymerisations and gain insights to the chemical Interestingly, the two chlorine atoms in 8 are arranged in a syn conformation.

Monomers 2 and 4 ,
[Rh(cod)(PPh 3 ) 2 ] + PF 6 − , [Rh(cod)(PPh 2 )(CH 2 ) 4 (PPh 2 )] + BF 4 − , and other chemicals and reagents were all purchased from Aldrich and used as received without further purification.M n,r , M w,r , and PDI (M w,r /M n,r ) values of the polymers were estimated by gel permeation chromatography (GPC) using a Waters Associates liquid chromatograph equipped with a Waters 515 HPLC pump, a set of Styragel columns (HT3, HT4, and HT6; molecular weight range 10 2 −10 7 ), a column temperature controller, a Waters 486 wavelength-tunable UV-vis detector, a Waters 2414 differential refractometer, and a Waters 2475 fluorescence detector.The polymers were dissolved in THF (~2 mg/mL) and filtered through 0.45 μm PTFE syringe-type filters before being injected into the GPC system.THF was used as eluent at a flow rate of 1.0 mL/min.The column temperature was maintained at 40 °C, and the working wavelength of the UV-vis detector was set at 254 nm.A set of monodisperse polystyrene standards (Waters) covering the molecular weight range of 10 3 −10 7 were used for the molecular weight calibration.M W,a values of the polymers were determined on a LLS spectrometer (ALV/DLS/SLS-5022F) equipped with a multi-τ digital time correlator (ALV5000) and a cylindrical 22 mW He−Ne laser (λ 0 = 632 nm, Uniphase) as light source.The dn/dC value at 632.8 nm

(
HRMS) were recorded on a GCT Premier CAB 048 mass spectrometer operating in an electronionization (EI) mode.Thermal gravimetric (TGA) analyses were conducted under nitrogen on a Perkin-Elmer TGA 7 analyzer at a heating rate of 10 °C/min.The thermal transitions were investigated by differential scanning colorimeter (DSC) using a TA Instruments DSC Q1000 at a heating rate of 10 °C/min.Cyclic Voltammetry (CV) measurement of the samples were performed in a three-electrode cell using a CHI-600D Electrochemical Workstation with 0.1 M tetra-n-butylammonium Electronic Supplementary Material (ESI) for Chemical Science This journal is © The Royal Society of Chemistry 2011 hexafluorophosphate ([n-Bu 4 N] + [PF 6 ] − ) in DCM as electrolyte at a scan rate of 100 mV/s under room temperature by purging Nitrogen before and between the measurement.A platinum wire was used as the counter electrode and a saturated calomel electrode (Hg/HgCl 2 /KCl) (SCE) was used as the reference electrode.The concentrations of the samples are 0.4 mg/mL in DCM.The HOMO energy levels were derived from the onset oxidation potentials (E onset-ox ) according to the equation: HOMO = −(E onset-ox + 4.4) eV, which is based on the energy level of SCE of −4.4 eV relative to vacuum.

Fig. S5
Fig. S5 Cyclic voltammograms of (A) model compounds 8, 9 and (B) polymers l-3a, hb-5a recorded in 0.1 M tetra-n-butylammonium hexafluorophosphate in DCM at a scan rate of 100 mV/s.Voltage values are reported versus SCE.The concentrations of the samples are 0.4 mg/mL.
Synthetic route to monomer 1cElectronic Supplementary Material (ESI) for Chemical Science This journal is © The Royal Society of Chemistry 2011 portions.After warmed to room temperature and stirred for 2 h, the mixture was poured into water and extracted with DCM.The organic layer was washed by saturated sodium thiosulfate solution and water, and dried over magnesium sulfate.After filtration and solvent evaporation, the crude product I 2 TPE was obtained in a yield of 92%.CuI (98 mg, 0.51 mmol), and 2-methylbut-3-yn-2-ol (2.6 g, 30.8 mmol), the mixture was heated to reflux for 12 h under nitrogen.The solvent was removed by rotary evaporation and the residue was extracted with DCM and water.The combined organic phases were dried over anhydrous MgSO 4 and concentrated using a rotary evaporator.The crude product was purified by silica-gel column chromatography to afford 2.2 g of white powder in an 87% yield.

Table 3 ,
no. 3).The solvent peaks (CDCl 3 and oxylene) are marked with asterisks.Supplementary Material (ESI) for Chemical Science This journal is © The Royal Society of Chemistry 2011 Electronic Supplementary Material (ESI) for Chemical Science This journal is © The Royal Society of Chemistry 2011