Three types of organic compounds--two carboxylic acids and an anhydride, were used as additives for polyketone （PK）. The effect of the additive structure and their feed ratios on the melting temperature, crystalliza...Three types of organic compounds--two carboxylic acids and an anhydride, were used as additives for polyketone （PK）. The effect of the additive structure and their feed ratios on the melting temperature, crystallization temperature, and crystallization rate of PK were studied. We found that the crystallization temperature could be reduced significantly by introducing a small quantity of organic additive, in particular, an anhydride. On addition of 1 phr of anhydride, the crystallization temperature was reduced by 10.7 ℃. Therefore, the non-isothermal crystallization kinetics of aliphatic PKJanhydride blends with various feed ratios was investigated using DSC. The results were analyzed by various theoretical models, such as Avrami, Ozawa and combined Avrami-Ozawa models.展开更多
In this research, the morphologies, isothermal-crystallization kinetics, and spherulite growth of aliphatic polyketone/polyamide-6 blends were studied. A single glass-transition temperature （Tg） was determined, and ...In this research, the morphologies, isothermal-crystallization kinetics, and spherulite growth of aliphatic polyketone/polyamide-6 blends were studied. A single glass-transition temperature （Tg） was determined, and the composition dependence of Tg for these blends was well described by the Kwei equation. The strong intermolecular interaction between the two polymer components was confirmed by melting-point depression. The isothermal-crystallization kinetics were analyzed on the basis of the Avrami approach. A linear increase in the radii of the spherulites with time was observed for all compositions. All the spherulites continued to grow at nearly identical growth rates. With increasing polyamide-6 content, the size of the spherulites in the polyketone/polyamide-6 blends gradually decreased, and the number of spherulites in the blends increased.展开更多
N-valeronitrile-N'-methylimidazolium hexafluorophosphate ([C 4 CNmim]+ PF 6),as a novel ionic liquid with polar nitrile functional group,was prepared.The structure of the ionic liquid was characterized by using IR...N-valeronitrile-N'-methylimidazolium hexafluorophosphate ([C 4 CNmim]+ PF 6),as a novel ionic liquid with polar nitrile functional group,was prepared.The structure of the ionic liquid was characterized by using IR and 1 H NMR.As a medium,the ionic liquid plays an important role in copolymerization of carbon monoxide (CO) with styrene (St).Some synthetic conditions were determined,including the usage of ionic liquid,palladium composite catalyst and methanol,CO pressure,reaction time and reaction temperature.The influence of these factors on catalytic activity was analyzed.The results show that the catalytic activity has reached 1 724.1 gStCO/(gPd·h) and the catalyst could be reused 5 times under the optimal condition:composite catalyst 0.015 mmol,ionic liquid 3 mL,methanol 0.75 mL,CO pressure 2MPa,reaction time 2 h and reaction temperature 70℃.This CO/St copolymerization within [C 4 CNmim]+ PF 6 system could facilitate ionic liquids with efficient and economical applications to polymeric materials.展开更多
In this study, we attempt to prepare a new blending system of poly（vinylidene fluoride） （PVDF） and aliphatic polyketone （POK） by melt compounding, The latter is a promising engineering plastic with comprehensive...In this study, we attempt to prepare a new blending system of poly（vinylidene fluoride） （PVDF） and aliphatic polyketone （POK） by melt compounding, The latter is a promising engineering plastic with comprehensive mechanical performances. When POK acted as minor phase to homogeneously disperse in and intimately contact with PVDF matrix, the brittle tensile behavior of neat PVDF transferred into a remarkably flexible manner （the elongation at break increased for 20 times）, and more interestingly, the room- temperature durability of β-form PVDF in the uniaxially drawn blend film was obviously better than that in the neat PVDF film. Fourier transform infrared spectroscopy revealed that specific dipole interaction existed between CF2 group of PVDF and C=O group of POK. The intermolecular dipolar interaction induced good compatibility in the PVDF/POK blends, as evidently proved by fine two-phase morphology and decreased melting points of POK crystals. Therefore, the good compatibility and interracial enhancement are responsible for the improvement of the stretch ductility and β-form room-temperature durability of the PVDF/POK blends.展开更多
The dipping method was devised to deposit Pd onto carbon nanotube as supported catalyst(Pd/CNT) for the copolymerization of carbon monoxide(CO) and styrene(ST) towards the formation of polyketone(PK).The Pd/CNT was ch...The dipping method was devised to deposit Pd onto carbon nanotube as supported catalyst(Pd/CNT) for the copolymerization of carbon monoxide(CO) and styrene(ST) towards the formation of polyketone(PK).The Pd/CNT was characterized by X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD) and high-resolution transmission electron microscopy(HRTEM).The construction and crystallization property of PK were evaluated by Fourier transform infrared spectroscopy(FTIR),13C-nuclear magnetic resonance(NMR) and XRD,respectively.The catalyst showed excellent activity and reusability in promoting the fabrication of PK.It can be recycled 14 times with the highest total catalytic activity of 4 239.64 gPK/(gPd·h) at Pd content of 8.63wt%.The results indicate that the prepared catalyst is effective to catalyze the copolymerization of CO and styrene.展开更多
A novel coordinated complex [(5-nitrophen)Pd(CF3CO2)2] (5-nitrophen = 5-nitro-1,10-phenanthroline) was first synthesized. By using XPS, IR, and 1H-NMR, its coordination unit was studied in comparison with those of com...A novel coordinated complex [(5-nitrophen)Pd(CF3CO2)2] (5-nitrophen = 5-nitro-1,10-phenanthroline) was first synthesized. By using XPS, IR, and 1H-NMR, its coordination unit was studied in comparison with those of complexes [(N-N)Pd(CH3CO2)2] and [(N-N)Pd(CF3CO2)2]. The H2,9 proton signals of 1H-NMR spectra of the complexes are excellent probes to monitor the evolution of the environment of the palladium atom. The state of anionic coordination was confirmed by the presence of IR absorption peaks of COO in complexes ([(N — N)Pd(CH3CO2)2] and [(N — N)Pd(CF3CO2)2]). Bonding energies of N1s and Pd3d5 obtained from XPS data testified to the strength of the N-Pd coordinating bond. The conclusion can be drawn by analyzing these data from IR, XPS and 1H-NMR that it is the unsymmetrical substitution of the 1,10-phenanthroline (phen) that makes the [(5-nitrophen)Pd(CF3CO2)2] more active. Experimental results showed that [(5-nitrophen)Pd(CF3CO2)2] exhibits much higher activity than [(bipy)Pd(CF3CO2)2] (1,1'- bipyridine = bipy) and [(phen)Pd(CF3CO2)2] under the same conditions.展开更多
Copolymerization of ethylene with carbon monoxide was pertormed with Cu catalyst systems. Novel catalystsystems based on Cu (Cu(CH_3COO)_2/ligand/acid) were firstly reported for the copolymerization of ethylene with c...Copolymerization of ethylene with carbon monoxide was pertormed with Cu catalyst systems. Novel catalystsystems based on Cu (Cu(CH_3COO)_2/ligand/acid) were firstly reported for the copolymerization of ethylene with carbonmonoxide, in which the ligand was a bidentate phosphorus chelating ligand. The experimental results showed that this kindof Cu catalyst system exhibited high activity. When DPPP (1, 3-bis(diphenylphosphine)propane) and CH_3COOH were usedas ligand and acid, the corresponding catalyst system had the best activity of 108.1 g copolymer/(gCu·h). The novel Cu catalyst system had the advantages of high stability and low cost.展开更多
Polyketone resins have been prepared by the Friedel-Crafts polymerization of dithiophenylidenecyclopentanone （I）, dithiophenylidenecyclohexanone （II） and dithiophenylideneacetone （III） with adipoyl, sebacoyl and...Polyketone resins have been prepared by the Friedel-Crafts polymerization of dithiophenylidenecyclopentanone （I）, dithiophenylidenecyclohexanone （II） and dithiophenylideneacetone （III） with adipoyl, sebacoyl and terephthaloyl dichlorides using boron trifluoride as catalyst and carbon disulphide as solvent. Polymers were characterized with IR, 1H- NMR, and the results showed the presence of carbonyl of ketonic groups in the main chain. The polyketones have inherent viscosities of 0.40-0.70 dL/g. All the polymers are semicrystalline and most of them are partially soluble in most common organic solvents but freely soluble in aprotic solvents. The temperatures of 50% weight loss are as high as 185℃ to 280℃ in air, indicating that these aromatic polyketones have excellent thermal stability. All the polyketones were tested for their antimicrobial activity against bacteria and fungi.展开更多
To lower the cost of polyketone synthesis, rare earth coordinate catalyst was introduced to the copolymerization of carbon monoxide （CO） and styrene （ST） to synthesize aliphatic polyketone STCO. The catalytic syst...To lower the cost of polyketone synthesis, rare earth coordinate catalyst was introduced to the copolymerization of carbon monoxide （CO） and styrene （ST） to synthesize aliphatic polyketone STCO. The catalytic system was composed of rare earth neodymium acetate, yttrium acetate, 2,2＇-bipyridine, p-toluensulfonic acid, cupric p-toluensulfonate, and 1 ,4-benzoquinone. The catalyst and the copolymer were characterized by infrared spectrum and X-ray photoelectron spectroscopy respectively. The effects of each component of catalytic system and the kinds of rare earth acetates on catalytic activity of copolymerization were investigated. The results show that the proposed rare earth has distinct catalytic activity in the copolymerization of CO and ST and the maximum activity can reach 303.3 gSTCO/（mol·h）.展开更多
The loaded catalyst was prepared by loading Pd2t on the ion exchange resin of polystyrene andused in the copolymerization of carbon monoxide(CO)with styrene(ST).The catalytic activity andusable life of the loaded cata...The loaded catalyst was prepared by loading Pd2t on the ion exchange resin of polystyrene andused in the copolymerization of carbon monoxide(CO)with styrene(ST).The catalytic activity andusable life of the loaded catalyst were investigated.Additionally the reuse of the waste Pd2+in thecopolymerization was studied by using the ion exchange resin.The results show that the Pd'+loadedcatalyst has some catalytic activity and reusability.The ion exchange resin D-72 can adsorb Pd2+,Cu2+,etc,in the waste of the copolymerization.The catalytic activity of the reused catalyst can reach 473.93g/(g Pd·h).展开更多
Room temperature ionic liquids as solvents for palladium-catalyzed copolymerization of carbon monoxide and styrene were prepared by reaction of aqueous lead tetrafluoroborate with correspond-ing chloride or bromide sa...Room temperature ionic liquids as solvents for palladium-catalyzed copolymerization of carbon monoxide and styrene were prepared by reaction of aqueous lead tetrafluoroborate with correspond-ing chloride or bromide salts. The recyclability of palladium composite catalyst in various ionic liquids was investigated. [Pd(bipy)2][BF4]2 showed a lower catalytic activity than [Pd(bipy)2][PF6]2 in similar conditions, although the catalytic activity of each composite catalyst in ionic liquids still existed after 4 successive recycles. It was shown the catalytic activity of palladium composite catalyst was higher than that of the catalyst formed in situ from palladium acetate, 2,2′-bipyridyl, and HA (A=PF6-, BF4-) in ionic liquids. The effects of volume of ionic liquids, reaction time, and the dosage of benzoquinone on the copolymerization were also studied.展开更多
The crosslinked polyacrylonitrile (PAN) wassynthesized by suspension polymerization using acrylonitrile(ANT) and divinylbenzene (DVB). Effects of a varietyof conditions on the polymerization of PAN particle sizeand st...The crosslinked polyacrylonitrile (PAN) wassynthesized by suspension polymerization using acrylonitrile(ANT) and divinylbenzene (DVB). Effects of a varietyof conditions on the polymerization of PAN particle sizeand stiffness were investigated. Polyketone was preparedby the copolymerization of carbon monoxide (CO) andstyrene (ST) catalyzed by PAN resin-supported palladiumacetate. The resin-supported catalyst and the copolymerizationproduct were characterized by infrared spectroscopy(IR) and Scanning Electron Microscopy (SEM). Effects ofthe components of a catalytic system and reaction time onthe catalytic activity were studied. The reusability of theresin-supported catalyst was also investigated.Results indicatedthat the resin-supported catalyst has excellent catalyticproperty. The yield of polyketone was 6.2348 g whenusing 1 g of resin and 22.4 mg of palladium acetate.展开更多
Here,we report the synthesis and the chain-lengthdependent self-assembling behaviors of discrete di-,tetra-,and hexaketones terminally functionalized with hydrogen-bonding carboxyl(C1,C2,and C3)and 3-acylaminopyridine...Here,we report the synthesis and the chain-lengthdependent self-assembling behaviors of discrete di-,tetra-,and hexaketones terminally functionalized with hydrogen-bonding carboxyl(C1,C2,and C3)and 3-acylaminopyridine groups(P1,P2,and P3).These polyketones were prepared by the coupling reactions of silylated analogues of 3,3-dimethylpentane-2,4-dione and t-butyl 2,2-dimethyl-3-oxobutanoate and the subsequent hydrolysis or amidation with 3-aminopyridine.Single-crystal Xray diffraction analysis revealed that C1 and C2 form helical assemblies in which the components are connected by the dimerization of terminal carboxyl groups,whereas the longer C3 showed infinite hydrogen-bonded chains mediated by 1,4-dioxane used as a crystallization solvent.Pyridine-terminated P1 exhibited a three-dimensional hydrogen-bonded network owing to multiple NH…N(pyridine)hydrogen bonds in the solid state.P2 generated a double-helix-like fiber structure in the crystalline state.Among the pyridine-terminated polyketones P1−P3,only P2 showed gelation behavior in chloroform(100 mM concentration)at 25℃.The scanning electron microscopy measurement of xerogel P2 revealed the formation of rod-like structures with a thickness of approximately 0.5−3.5μm.These results demonstrate that the precise control of the polyketone chain length can significantly alter hydrogen-bonded self-assembly in the solid state and in solution even with the same terminal structures.展开更多
文摘Three types of organic compounds--two carboxylic acids and an anhydride, were used as additives for polyketone （PK）. The effect of the additive structure and their feed ratios on the melting temperature, crystallization temperature, and crystallization rate of PK were studied. We found that the crystallization temperature could be reduced significantly by introducing a small quantity of organic additive, in particular, an anhydride. On addition of 1 phr of anhydride, the crystallization temperature was reduced by 10.7 ℃. Therefore, the non-isothermal crystallization kinetics of aliphatic PKJanhydride blends with various feed ratios was investigated using DSC. The results were analyzed by various theoretical models, such as Avrami, Ozawa and combined Avrami-Ozawa models.
文摘In this research, the morphologies, isothermal-crystallization kinetics, and spherulite growth of aliphatic polyketone/polyamide-6 blends were studied. A single glass-transition temperature （Tg） was determined, and the composition dependence of Tg for these blends was well described by the Kwei equation. The strong intermolecular interaction between the two polymer components was confirmed by melting-point depression. The isothermal-crystallization kinetics were analyzed on the basis of the Avrami approach. A linear increase in the radii of the spherulites with time was observed for all compositions. All the spherulites continued to grow at nearly identical growth rates. With increasing polyamide-6 content, the size of the spherulites in the polyketone/polyamide-6 blends gradually decreased, and the number of spherulites in the blends increased.
基金Supported by National Natural Science Foundation of China (No.20476080)Tianjin Natural Science Foundation (No.07JCYBJC00600)
文摘N-valeronitrile-N'-methylimidazolium hexafluorophosphate ([C 4 CNmim]+ PF 6),as a novel ionic liquid with polar nitrile functional group,was prepared.The structure of the ionic liquid was characterized by using IR and 1 H NMR.As a medium,the ionic liquid plays an important role in copolymerization of carbon monoxide (CO) with styrene (St).Some synthetic conditions were determined,including the usage of ionic liquid,palladium composite catalyst and methanol,CO pressure,reaction time and reaction temperature.The influence of these factors on catalytic activity was analyzed.The results show that the catalytic activity has reached 1 724.1 gStCO/(gPd·h) and the catalyst could be reused 5 times under the optimal condition:composite catalyst 0.015 mmol,ionic liquid 3 mL,methanol 0.75 mL,CO pressure 2MPa,reaction time 2 h and reaction temperature 70℃.This CO/St copolymerization within [C 4 CNmim]+ PF 6 system could facilitate ionic liquids with efficient and economical applications to polymeric materials.
基金supported by the National Natural Science Foundation of China (Nos. 51373108 and 21574088)
文摘In this study, we attempt to prepare a new blending system of poly（vinylidene fluoride） （PVDF） and aliphatic polyketone （POK） by melt compounding, The latter is a promising engineering plastic with comprehensive mechanical performances. When POK acted as minor phase to homogeneously disperse in and intimately contact with PVDF matrix, the brittle tensile behavior of neat PVDF transferred into a remarkably flexible manner （the elongation at break increased for 20 times）, and more interestingly, the room- temperature durability of β-form PVDF in the uniaxially drawn blend film was obviously better than that in the neat PVDF film. Fourier transform infrared spectroscopy revealed that specific dipole interaction existed between CF2 group of PVDF and C=O group of POK. The intermolecular dipolar interaction induced good compatibility in the PVDF/POK blends, as evidently proved by fine two-phase morphology and decreased melting points of POK crystals. Therefore, the good compatibility and interracial enhancement are responsible for the improvement of the stretch ductility and β-form room-temperature durability of the PVDF/POK blends.
基金Supported by the National Natural Science Foundation of China(No.20476080)Tianjin Natural Science Foundation(No.07JCYBJC00600)
文摘The dipping method was devised to deposit Pd onto carbon nanotube as supported catalyst(Pd/CNT) for the copolymerization of carbon monoxide(CO) and styrene(ST) towards the formation of polyketone(PK).The Pd/CNT was characterized by X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD) and high-resolution transmission electron microscopy(HRTEM).The construction and crystallization property of PK were evaluated by Fourier transform infrared spectroscopy(FTIR),13C-nuclear magnetic resonance(NMR) and XRD,respectively.The catalyst showed excellent activity and reusability in promoting the fabrication of PK.It can be recycled 14 times with the highest total catalytic activity of 4 239.64 gPK/(gPd·h) at Pd content of 8.63wt%.The results indicate that the prepared catalyst is effective to catalyze the copolymerization of CO and styrene.
基金This project was supported by the National Natural Science Foundation of China (Grant No. 20244001).
文摘A novel coordinated complex [(5-nitrophen)Pd(CF3CO2)2] (5-nitrophen = 5-nitro-1,10-phenanthroline) was first synthesized. By using XPS, IR, and 1H-NMR, its coordination unit was studied in comparison with those of complexes [(N-N)Pd(CH3CO2)2] and [(N-N)Pd(CF3CO2)2]. The H2,9 proton signals of 1H-NMR spectra of the complexes are excellent probes to monitor the evolution of the environment of the palladium atom. The state of anionic coordination was confirmed by the presence of IR absorption peaks of COO in complexes ([(N — N)Pd(CH3CO2)2] and [(N — N)Pd(CF3CO2)2]). Bonding energies of N1s and Pd3d5 obtained from XPS data testified to the strength of the N-Pd coordinating bond. The conclusion can be drawn by analyzing these data from IR, XPS and 1H-NMR that it is the unsymmetrical substitution of the 1,10-phenanthroline (phen) that makes the [(5-nitrophen)Pd(CF3CO2)2] more active. Experimental results showed that [(5-nitrophen)Pd(CF3CO2)2] exhibits much higher activity than [(bipy)Pd(CF3CO2)2] (1,1'- bipyridine = bipy) and [(phen)Pd(CF3CO2)2] under the same conditions.
文摘Copolymerization of ethylene with carbon monoxide was pertormed with Cu catalyst systems. Novel catalystsystems based on Cu (Cu(CH_3COO)_2/ligand/acid) were firstly reported for the copolymerization of ethylene with carbonmonoxide, in which the ligand was a bidentate phosphorus chelating ligand. The experimental results showed that this kindof Cu catalyst system exhibited high activity. When DPPP (1, 3-bis(diphenylphosphine)propane) and CH_3COOH were usedas ligand and acid, the corresponding catalyst system had the best activity of 108.1 g copolymer/(gCu·h). The novel Cu catalyst system had the advantages of high stability and low cost.
文摘Polyketone resins have been prepared by the Friedel-Crafts polymerization of dithiophenylidenecyclopentanone （I）, dithiophenylidenecyclohexanone （II） and dithiophenylideneacetone （III） with adipoyl, sebacoyl and terephthaloyl dichlorides using boron trifluoride as catalyst and carbon disulphide as solvent. Polymers were characterized with IR, 1H- NMR, and the results showed the presence of carbonyl of ketonic groups in the main chain. The polyketones have inherent viscosities of 0.40-0.70 dL/g. All the polymers are semicrystalline and most of them are partially soluble in most common organic solvents but freely soluble in aprotic solvents. The temperatures of 50% weight loss are as high as 185℃ to 280℃ in air, indicating that these aromatic polyketones have excellent thermal stability. All the polyketones were tested for their antimicrobial activity against bacteria and fungi.
基金Supported by National Natural Science Foundation of China (No. 20476080).
文摘To lower the cost of polyketone synthesis, rare earth coordinate catalyst was introduced to the copolymerization of carbon monoxide （CO） and styrene （ST） to synthesize aliphatic polyketone STCO. The catalytic system was composed of rare earth neodymium acetate, yttrium acetate, 2,2＇-bipyridine, p-toluensulfonic acid, cupric p-toluensulfonate, and 1 ,4-benzoquinone. The catalyst and the copolymer were characterized by infrared spectrum and X-ray photoelectron spectroscopy respectively. The effects of each component of catalytic system and the kinds of rare earth acetates on catalytic activity of copolymerization were investigated. The results show that the proposed rare earth has distinct catalytic activity in the copolymerization of CO and ST and the maximum activity can reach 303.3 gSTCO/（mol·h）.
基金Supported by Tianjin Natural Science Foundation(No.983603811).
文摘The loaded catalyst was prepared by loading Pd2t on the ion exchange resin of polystyrene andused in the copolymerization of carbon monoxide(CO)with styrene(ST).The catalytic activity andusable life of the loaded catalyst were investigated.Additionally the reuse of the waste Pd2+in thecopolymerization was studied by using the ion exchange resin.The results show that the Pd'+loadedcatalyst has some catalytic activity and reusability.The ion exchange resin D-72 can adsorb Pd2+,Cu2+,etc,in the waste of the copolymerization.The catalytic activity of the reused catalyst can reach 473.93g/(g Pd·h).
基金National Natural Science Foundation of China (No.20476080)Natural Science Foundation of Tianjin (No.07JCYBJC00600)
文摘Room temperature ionic liquids as solvents for palladium-catalyzed copolymerization of carbon monoxide and styrene were prepared by reaction of aqueous lead tetrafluoroborate with correspond-ing chloride or bromide salts. The recyclability of palladium composite catalyst in various ionic liquids was investigated. [Pd(bipy)2][BF4]2 showed a lower catalytic activity than [Pd(bipy)2][PF6]2 in similar conditions, although the catalytic activity of each composite catalyst in ionic liquids still existed after 4 successive recycles. It was shown the catalytic activity of palladium composite catalyst was higher than that of the catalyst formed in situ from palladium acetate, 2,2′-bipyridyl, and HA (A=PF6-, BF4-) in ionic liquids. The effects of volume of ionic liquids, reaction time, and the dosage of benzoquinone on the copolymerization were also studied.
基金the National Natural Science Foundation of China(Grant No.20476080).
文摘The crosslinked polyacrylonitrile (PAN) wassynthesized by suspension polymerization using acrylonitrile(ANT) and divinylbenzene (DVB). Effects of a varietyof conditions on the polymerization of PAN particle sizeand stiffness were investigated. Polyketone was preparedby the copolymerization of carbon monoxide (CO) andstyrene (ST) catalyzed by PAN resin-supported palladiumacetate. The resin-supported catalyst and the copolymerizationproduct were characterized by infrared spectroscopy(IR) and Scanning Electron Microscopy (SEM). Effects ofthe components of a catalytic system and reaction time onthe catalytic activity were studied. The reusability of theresin-supported catalyst was also investigated.Results indicatedthat the resin-supported catalyst has excellent catalyticproperty. The yield of polyketone was 6.2348 g whenusing 1 g of resin and 22.4 mg of palladium acetate.
基金a JSPS Grant-in-Aid for Challenging Research(Exploratory)(No.20K21214)Scientific Research(B)(No.22H02058)+3 种基金JST FOREST Program(No.JPMJFR211H)Nagase Science and Technology Foundation of which Y.Inokuma is the principal investigatorThe Institute for Chemical Reaction Design and Discovery(ICReDD)was established by the World Premier International Research Initiative(WPI),MEXT,Japan.Y.Ide is grateful for a Grant-in-Aid for Early-Career Scientists grant(No.21K14597)and Scientific Research on Innovative Areas“Soft Crystals”.Y.M.would like to acknowledge the Grant-in-Aid for JSPS Research Fellow(No.21J11228)。
文摘Here,we report the synthesis and the chain-lengthdependent self-assembling behaviors of discrete di-,tetra-,and hexaketones terminally functionalized with hydrogen-bonding carboxyl(C1,C2,and C3)and 3-acylaminopyridine groups(P1,P2,and P3).These polyketones were prepared by the coupling reactions of silylated analogues of 3,3-dimethylpentane-2,4-dione and t-butyl 2,2-dimethyl-3-oxobutanoate and the subsequent hydrolysis or amidation with 3-aminopyridine.Single-crystal Xray diffraction analysis revealed that C1 and C2 form helical assemblies in which the components are connected by the dimerization of terminal carboxyl groups,whereas the longer C3 showed infinite hydrogen-bonded chains mediated by 1,4-dioxane used as a crystallization solvent.Pyridine-terminated P1 exhibited a three-dimensional hydrogen-bonded network owing to multiple NH…N(pyridine)hydrogen bonds in the solid state.P2 generated a double-helix-like fiber structure in the crystalline state.Among the pyridine-terminated polyketones P1−P3,only P2 showed gelation behavior in chloroform(100 mM concentration)at 25℃.The scanning electron microscopy measurement of xerogel P2 revealed the formation of rod-like structures with a thickness of approximately 0.5−3.5μm.These results demonstrate that the precise control of the polyketone chain length can significantly alter hydrogen-bonded self-assembly in the solid state and in solution even with the same terminal structures.
