Modern Polymer Spect..

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135s 9 1 Ms1i 122Wbr 147 NH ob(37) CO ob(16) NC' s(13) H" b2(101 118 CNC" d(21) NC" C d(18) CTN d(13) NH ob(l?i 104 NH...O ib(27) CN t(21) Cp b1115~ 103 NH.,.O ibi331 CN t(21) NH obi2O) C"C t(15) CO,..H t(l1) 91 Cp bl(26) NH ob( 19) H-.O s( 14) C"C t( 11) 87 H...O ~(33) CNC" d(17) CN t(l1) CN'C d(10) 74 C'C t(24) NC" ti22)H.,.O ~(22) CN t(15) 41 CO...H ib(21) NH ob(70) Cpblilhj NH...O ib(l5) NH...O ti 12) 32 NH.,.O ib(371 CO-.H ib(22) CN t(l5) 31 H...O s(15) CO...H t(l5) CO...H ib(14) NH...O ib(l4) NH...O t( 12) NH ob( 11 j CN t( 10) 19 CO,.,H ti35) NH...O t(27) CO.,.H ib(l4) H". . .H' sil3j a Data taken from [88]. S: strong, M: medium, W: weak, V: very, sh: shoulder, br: broad, 11: parallel dichroism, I: perpendicular dichroism. b s: stretch, as: antisymmetric stretch, ss: symmetric stretch, b: bend, ib: in-plane bend, ob: out-of-plane bend, ab: antisymmetric bend, sb: symmetric bend, r: rock, d: deforniation, t: torsion. Contributions 2 10.
966 5 Vibr-atioiial Slm-troscopj, of' Pol.vpeptides empirical force field is capable of giving very acceptable frequency agreement: the rms error between observed and calculated frequencies is 5.9 cm-'. Second, the character of the symmetry species is well predicted: A species modes exhibit only Rainan activity, B1 and B? species modes exhibit 1) and I IR dichroism. respectively. Third, while the agreement is somewhat poorer, band shifts on N-deuteration are reasonably well accounted for [88] (for amide I the observed downshift of 4 cn-' is reproduced exactly by the calculation). Finally, TDC is crucial to explaining the large splittings in the amide I and amide I1 modes: in its absence the ainide I modes are calculated at 1670 (A), 1673 (B,), 1665 (B2), and 1670 (B3j cin-.', and the amide I1 modes are predicted at 1545 (A), 1549 (BI), 1550 (B?), and 1554 (B3) c111-l [5]. With respect to the amide modes, a comparison with the results of the ah initio calculation on the hydrogen-bonded Ala dipeptide is of interest, even though the force fields are different. Although localized primarily in CO s, the amide I modes of /I-PLA are constrained by symmetry to be coupled modes of the four peptide groups in the unit cell. Interestingly, CN s is now the second major component compared with NH ib foi- the Ala dipeptide. The coupled amide I1 modes contain, in addition to NH ib and CN s, C"C s and CO ib contributions not present (at the level of 2 10) in the Ala dipeptide. With respect to the strong amide 111 modes, at 1243 and 1224 cni-', H" b dominates and NC" s also contributes in addition to NH ib and CN s. As noted above, NH ib is a contributor to many other modes in the 1400-1200 cm-l region. The amide V modes are well accounted for, and in particular the observed absence of any significant dichroism in this band 1911 is explained by the near coincidence in frequency of the predicted B1 and B3 species modes. Besides the aniide modes, local as well as other skeletal modes are very well accounted for. The excellent agreement obtained for /I-PLA would indicate that this force field should be transferable to other APPS polypeptides, of course taking due account of side-chain differences. This has been done for Ca-poly( L-glutamate), Ca-PLG (921, which X-ray and electron diffraction data had indicated to have an APPS structure but which were not extensive enough to provide a definitive conclusion. A proposed model [93] was used as the basis for the vibrational analysis, and the good prediction of the observed bands [92] supports both the model as well as the viability of the force field. The subtle differences between the P-PLA and /I-Ca-PLG spectra are accounted for by the normal mode calculation, and emphasize the influence of the side chain on the main-chain modes, particularly on amide 111. A similar successful vibrational analysis has been done on an alternating copolymer, APPS poly( L-alanylglycine) [ 191. Antiparallel-Chain Rippled Sheet Although early studies assumed that PG also adopts an APPS structure, electron diffraction studies of 'single crystals' and oriented thin films [94] suggested that extended-chain PG, PGI, has an APRS structure. This was supported by conforniational energy calculations [95], and was the basis for a detailed vibrational analysis of the PGI spectra [19, 961, strongly confirming this proposal. (Since the
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Modern Polymer Spectroscopy Edited
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Modern Polymer Spectroscopy Edited
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Preface For unfortunate reasons the
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However, theory and calculations yi
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Contents 1 Two-Dimensional Infrared
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Con ten t~ xi Index 5.2 Force Field
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Contributors M. Del Zoppo Dipartime
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1 Two-Dimensional Infrared (2D IR)
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1.2 Brick~qrorrnrl 3 . Figure 1-3.
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1.0 , Figure 1-6. The in-phtrse and
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1.2 Bcrckgroinizd 7 where AA (i~) i
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1.2 Background 9 1.2.5 Two-Dimensio
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1.3 Bnsic Properties of 20 IR Corre
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2D IR spectrometer coupled with a d
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1.5 Applirtrtions 15 Unlike a dispe
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\ '\ Melliyleiie 1'7- -3000 Posiliv
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11 Amorphous Crystalline ,...." I F
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1.5 Applications 21 / I 1430 Figure
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1.5 Appliccitioiis 23 Methylene Fig
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1.5 Ajqdicrrtions 25 3024 Figure 1-
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1.5 Applicutions 27 Furthermore. th
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1.7 Coizclirsions 29 derived in a s
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1.9 References 31 [9] Colthup, N. B
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2 Segmental Mobility of Liquid Crys
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SRMPLE/DETECTOR e3 ‘retardation
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2.4 Srvuc me-Dependenr Alignment 37
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2.5 Electric Field-Innductid Orirnt
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2.5 Electric Field-nclticetl Orient
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a -@ COWER SRHPLE ._ 2.5 Elec tric
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2.5 Electric Field-Itzduced Orienta
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2.5 Electric Field-IwrElrced Orient
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2.5 Electric Field-Im/irced Orientu
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2.5 Electric Field-Induced Orientli
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2.5 Electric Field-Induced Orientat
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2.5 Electric Field-Induced Orienfat
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2.5 Elrc tric Field-Iiidircwl Orim
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2500 2008 I s00 WRVtNdMRtR CM-I Fig
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-3.6 Aligmient OJ' Side- Clinin Liy
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~ polyester 2.6 Alignnient qf Side-
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I." 0.9 0.8 Figure 2-34. FTlR 0.7 p
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induced alignment of the investigat
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2.7 Orientation oj Liquid Ci:i,stal
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2.7 Orieritation of Liquid Ciysttrl
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0 8 18 16 1 a W u z a m a 0 Ln m Q
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2.7 Orientation oj Liquid Crystals
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2.7 Orientation of Liquid Crjvtals
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2.7 Orientatioiz of Liquid Crystals
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2.8 Conclusions 81 strain. As A0 is
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3. I0 Refcreiice.r 83 [I 71 Hoffina
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2.10 References 85 [92] Wiesner, U.
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t Order/Disorder in Chain Molecules
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onds which hold atoms together thro
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3.2 The Dyriamical Case qf Simll ar
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3.2 The Dyrinniical Case of Sinnll
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3.4 S11or.f- and Loizg-Rcrizye Vibr
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3.4 Slzort- and Loiig-Range Vibrati
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eyularity), e.g., 2. During the pol
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3.5 Towards Lnrger Molecules: From
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3.5 TOIIYW~ Laiyer Molertiles: Fvoi
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3.5 Towmu" Larger Molecules: F~om O
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1700 - CIO --- ca c 22 _- c 12 l l
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3.6 From Dynamics to Vibrational Sp
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3.6 Froin Dynaiiiics to T’ihratio
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3.7 The Case of Isotactic Polypropy
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3.7 The Cuse of Isotactic Polypvop.
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3.8 Density of Vibrational States a
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3.8 Dtvz.sit,v of L’ihrntioizal S
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3.8 Driisity of Vibratioiid StLitrs
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3 9 Mouiiiq ToIvmds Rerrlitv: From
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3.9 Moving Towards Reality: From Or
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3.9 Moving Towards Reality: Froin O
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3.10 Wlmt Do We Learn from Cnlcailc
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+ 3.11 A Very Siriiple Ccrse: Latti
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3 I1 A Yey) Siiiiple Case: LLittice
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3.11 A Vq> Siiiiplc Crrw: Luttice D
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Figure 3-22. Sample eigenvectors in
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3.12 CIS-trans Opening @the Double
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3.13 Defect Modes cis Structtrr.al
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3.13 Defect Mo&s cis Structurcil Pr
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0 3.14 Case Studies N 0 d - Y N o m
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3.14 Case Studies 147 OC 60 58 57.
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3.14 Case Studies 149 GI A V E N U
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3.14 Case Studies 15 1 correspond t
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3.14 Case Studies 153 (I10 + 200) +
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3.14 Case Studies 155 1500 1480 146
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3.14 Case Studies 157 the molecular
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17E (ir 1, R): (iii) z = 4, t = 1,
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3.16 Stnictural Znlioi~zogeneity an
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3.1 7 Fermi Resonancrs 163 stants.
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3.1 7 Femi Resorinnces 165 2 L 1 29
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lowing. The CHl-bending mode 6 [cer
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3.17 Ferini Re.sonrriire.s 169 a Fi
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3. I7 Fernii Resoiiances 17 1 terin
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3.18 Band Broadening and Confonnati
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3.18 Bmd Brourleiziriy md Cmforrnat
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3.18 Band Bvoaderiing arid Conjonna
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3.18 Band Broadening and Confornmti
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3.19 A Worked E.utinple 181 pre-mel
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3.19 A Wovh-ecl E.uanzple 183
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3.19 A Worked Example 185 19 5°C 2
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3.19 A Workrd Example 187 Figure 3-
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3.19 A Worked E.rcnniplr 189 LAM I
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3.19 A Worked E.xuniple 191 Figure
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3.19 A Worked E.vnn~yle 193 Figure
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3.19 A Worked E.vnrqde 195 009.1 00
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3.19 A Worked Example 197 existence
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3.1 9 A Worked Example 199 The soli
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3.20 References 201 very important,
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3.20 References 203 [41] M. Gussoni
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3.20 Refeeveiicrs 205 [I 171 P. Jon
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4 Vibrational Spectroscopy of Intac
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4.3 Georrietvy oj Intuct Po1vniev.r
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1'45 4.4 Geometric Chunges I?zditce
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4.4 Geometric Chmges Iiid~lrcecl bj
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Page 232 and 233: 4.7 Poly(p-pheiq.lene) 217 with an
Page 234 and 235: 4.7 Pol)~(p-pheiz~~lene) 219 ENERGY
Page 236 and 237: is worthwhile pointing out that the
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Page 240 and 241: 4.7 Poly(y-phenylene) 225 Figure 4-
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Page 246 and 247: under various models. According to
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Page 252 and 253: 4.12 References 237 [98j Matsunuma,
Page 254 and 255: 5 Vibrational Spectroscopy of Polyp
Page 256 and 257: 5.2 FOYCC Fields 241 such calculati
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Page 260 and 261: 5.2 Force Fields 245 centers of the
Page 262 and 263: 5.2 Force Fields 247 ture with conf
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Page 266 and 267: 5.3 Ainide Modes 251 Table 5-1. Ami
Page 268 and 269: Table 5-2. Some amide modes of four
Page 270 and 271: 5.3 Amidc Modes 255 Figure 5-1. Opt
Page 272 and 273: 5.4 Polypeptides 257 nonhydrogen-bo
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Page 276 and 277: I 5.4 Polypeptides 261 )I .- + $ 80
Page 278 and 279: 1226M 1222s (1 1165W 1167s (1 1120V
Page 282 and 283: 5.4 Polypeptides 267 glycine residu
Page 284 and 285: 5.4 Polypeptides 269 Raman bands in
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Page 288 and 289: Frequency (cm-'1 100% b 700 500 300
Page 290 and 291: 5.4 Polypptidt~s 215 Table 5-9. Obs
Page 292 and 293: ~~ ~~ ~~~ ~ ~ ~~ 5.4 Polypeptides 2
Page 294 and 295: 5.4 Poliyeptides 219 Table 5-11. Co
Page 296 and 297: Table 5-12. Aniide mode frequencies
Page 298 and 299: 1351 Lifson, S., Stern, P. S., J. C
Page 300 and 301: 5.6 Refeverices 285 [130] Tiffany,
Page 302 and 303: Index Amide modes 249 Amorphous pol
Page 304 and 305: Step-scan FTIR spectroscopy 14,34 -
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