Two- and Three-Dimensional Smectic Ordering of Single-Handed Helical Polymers(11)

9

VOL.130,NO.1,2008

Onouchietal.

formshowinganLCphaseonapoly(tetrafluoroethylene)(PTFE)petridish.Aftergradualevaporationofthesolvent,thecastfilmwasannealedat170°Cfor2days.Theobtainedcastfilmwasembeddedinepoxyresin(ThreeBond2082C)andultramicrotomedperpendiculartothecastfilmsurface.Thethinfilm(ca.30nmthick)wasthenstainedbyRuO4vaporfor7minbeforetheTEMobservations.

Materials.Anhydrouschloroformandtoluene(watercontent<50ppm)werepurchasedfromAldrichandstoredunderdrynitrogen.THFwasdriedoversodiumbenzophenoneketyl,distilledontoLiAlH4undernitrogen,anddistilledunderhighvacuumjustbeforeuse.The4-isocyanobenzoyl-L-andD-alaninedecylesters(L-1andD-1)8andtheµ-ethynediylPt-Pdcomplex(2)10werepreparedaspreviouslyreported.Polymerization.ThepolymerizationofL-1wascarriedoutinadryglassampuleunderadrynitrogenatmosphereusing2asthecatalystindryTHF.Atypicalexperimentalprocedureisdescribedbelow.MonomerL-1(300mg,0.84mmol)wasplacedinadryampule,whichwasthenevacuatedonavacuumlineandflushedwithdrynitrogen.Afterthisevacuation-flushprocedurehadbeenrepeatedthreetimes,athree-waystopcockwasattachedtotheampule,anddryTHF(3.4mL)wasaddedbyasyringe.Tothiswasaddedasolutionof2inTHF(10µM,0.81mL)atambienttemperature.TheconcentrationsofL-1and2were0.2and0.002M,respectively([1]/[2])100).Themixturewasthenstirredunderadrynitrogenatmosphereandheatedto55°C.After20h,theresultingpolymer(poly-L-1)wasprecipitatedinalargeamountofmethanol,collectedbycentrifugation,anddriedinvacuoatroomtemperatureovernight(286mg,96%yield).

Spectroscopicdataofpoly-L-1:IR(KBr,cm-1):3277(νN-H),1750(νCdOester),1635(amideI),1535(amideII);1HNMR(CDCl3,55°C):δ0.87(broad,CH3,3H),1.26(broad,CH2,14H),1.53(broad,CH3andCH2,5H),4.09(broad,CH2,2H),4.51(broad,CH,1H),4.8-7.7(broad,aromatic,4H),7.9-9.0(broad,NH,1H);[R]25D-995°(c0.1,chloroform);Anal.Calcd(%)for(C21H30N2O3)n:C,70.36;H,8.44;N,7.81.Found:C,70.23;H,8.56;N,7.68.

Fractionation.Theobtainedpoly-L-1(70.8mg)wassuspendedin30mLofacetone,andthemixturewasstirredatambienttemperaturefor3h.Afterfiltration,thefiltratewasevaporatedtodrynessunderreducedpressure,givingpoly-L-1(+)(10.0mg,14%).Theacetone-insolublepolymerwasdissolvedinasmallamountofchloroform,thesolutionwasprecipitatedinalargeamountofacetone,andtheprecipitatewasthencollectedbyfiltration.Afterthisprocedurewasrepeatedagain,thepoly-L-1(-)wasobtained(44.5mg,63%).

Spectroscopicdataofpoly-L-1(+):IR(KBr,cm-1):3279(νN-H),1750(νCdOester),1635(amideI),1535(amideII);1HNMR(CDCl3,55°C):δ0.90(broad,CH3,3H),1.29(broad,CH2,14H),1.62(broad,CH3andCH2,5H),4.11(broad,CH2,2H),4.51(broad,CH,1H),4.9-7.7(broad,aromatic,4H),8.3-9.0(broad,NH,1H);[R]25D+1530°(c0.05,chloroform).Anal.Calcd(%)for(C21H30N2O3)n:C,70.36;H,8.44;N,7.81.Found:C,70.18;H,8.44;N,7.78.

Spectroscopicdataofpoly-L-1(-):IR(KBr,cm-1):3282(νN-H),1750(νCdOester),1635(amideI),1535(amideII);1HNMR(CDCl3,55°C):δ0.87(broad,CH3,3H),1.25(broad,CH2,14H),1.53(broad,CH3andCH2,5H),4.09(broad,CH2,2H),4.51(broad,CH,1H),4.8-7.7(broad,aromatic,4H),7.9-8.9(broad,NH,1H);[R]25D-1615°(c0.1,chloroform).Anal.Calcd(%)for(C21H30N2O3)n:C,70.36;H,8.44;N,7.81.Found:C,70.35;H,8.36;N,7.64.

Poly-D-1wasalsopreparedbythepolymerizationofD-1with2([1]/[2])100)inthesamewayasdescribedabove,andtheacetone-insolublepart(poly-D-1(+))wasobtainedbyfractionationwithacetone.Spectroscopicdataofpoly-D-1:IR(KBr,cm-1):3276(νN-H),1751(νCdOester),1635(amideI),1535(amideII);1HNMR(CDCl3,55°C):δ0.87(broad,CH3,3H),1.26(broad,CH2,14H),1.54(broad,CH3andCH2,5H),4.10(broad,CH2,2H),4.52(broad,CH,1H),4.9-7.7(broad,aromatic,4H),8.0-9.1(broad,NH,1H);[R]25D+1062°(c0.05,chloroform).Anal.Calcd(%)for(C21H30N2O3)n:C,70.36;H,8.44;N,7.81.Found:C,70.36;H,8.32;N,7.64.

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