An IR spectroscopy and high resolution 1H NMR study of polyphenylacetylene microstructures

IR spectroscopy and high resolution IH NMR study of PPA microstructures

1539

REFERENCES I. Ye. S. KRONGAUZ, Uspekhi khimii 46: 112, 1977 2. A.L. RUSANOV, S. N. LEONTEVA and Ts. G. IREMASHVILI, Uspekhi khimii 46: 151, 1977 3. V. V. KORSHAK, Ye. S. KRONGAUZ, A. L. RUSANOV, A. P. TRAVNIKOVA, N. M. KOFMAN, T. V. LEKAYE, D. VOROBEV and N. S. ZABELNIKOV, Russian Pat. 677434 4. V.V. KORSHAK, A.L. RUSANOV, A. M. BERLIN, S. Kh. FIDLER and F.I. ADYRKHAYEVA, Vysokomol. soyed. A21: 68, 1979 (Translated in Polymer Sci. U.S.S.R. 21: 1, 75, 1979) 5. V. V. KORSHAK, S. S. A. PAVLOVA, P. N. GRIBKOVA, I. V. VLASOVA, T. V. LEKAYE, A. L. RUSANOV and Ye. S. KRONGAUZ, Vysokomol. soyed. B22: 916, 1980 (Not translated in Polymer Sci. U.S.S.R.) 6. D. V. VAN-KREVELEN, Advances in the Chemistry of Thermally Stable Polymers. (Ed. Z. Edlinski), Warsaw, 1974 7. V. V. KORSHAK, A. L. RUSANOV, A. M. BERLIN, S. Kh. FIDLER, B. R. LIFSHITS, T. Kh. DYMSHITS, L. N. SILYUTINA and V. F. BLINOV, Vysokomol. soyed. A21: 657, 1979 (Translated in Polymer Sci. U.S.S.R. 21: 3, 719, 1979)

Polymer Science U.S.S.R. Vol. 30, No. 7, pp. 1539-1546,1988

0032-3950188 $10.00+ .00

Printedin Poland

O 1989PergamonPre~ plc

AN IR SPECTROSCOPY

AND

HIGH

RESOLUTION IH NMR STUDY OF POLYPHENYLACETYLENE MICROSTRUCTURES* M . G . CHAUSER, L. S. KOL'TSOVA, L. V. VLADIMIROV, "Y'A. G. URMAN, S . G. ALEKSEYEVA, N. L. ZAICHENKO,

E. F. OL~INm and M. I. CH~KASHIN Institute of Chemical Physics, U.S.S.R. Academy of Sciences (Received 5 November 1987)

Data are given on the IR spectra of polyphenylacetylenes obtained on polymerization of phenylacetylene under the action of heat (A), WCI6 (B), AI(C2Hs)3-TiCI2 (C), and Co(AcAc)a-AI(C2Hs)a (13). In their cis-unit content the polyphenylacetylenes studied can be arranged in the series D > C > B > A, which is in agreement with high resolution IH NMR spectroscopy data. According to this data polymer A is constructed from trans- and cyclohexadiene fragments, and polymers B and D mainly from linear cis. and trans-units.

IT IS known, [1-4] that in polyphenylacetylenes (PPA) the monomer units are connected together in a "head to tail" sequence and can have four types of configuration differing in the position of the chain relative to the double and single bonds: trans-trans (I), trans-cis (II), cis-cis (III), and cis-trans (IV). The proposition that the PPA * Vysokomol. soyed. A30: No. 7, 1464-1469, 1988.

1540

M . G . CRAUS~X et at.

m a c r o m o l e c u l e s can c o n t a i n c y c l o h e x a d i e n e f r a g m e n t s [5, 6] has been c o n f i r m e d [3, 4], \

R

C--H

!

\c ~

C--H

R--C ~

\

ic

\c-n R--C ~

\c-a R_C~

n

H/ ~C/ R

\C--H R--C

H

C

~~rt

H/

/

H

~t

l~ m

C

\C / ~n C H R/

~

\

f

CII

I I

H

R/ \c/"

JC

\C/" %H C n

C .~ II

\

R II

IV

where R = C6Hs. I n this w o r k the m i c r o s t r u c t u r e o f P P A o b t a i n e d o n t h e r m a l p o l y m e r i z a t i o n o f p h e n y l a c e t y l e n e ( P P A T ) a n d f l - d e u t e r o p h e n y l a c e t y l e n e ( P D P A ) a n d also on p o l y m e r i z a t i o n o f p h e n y l a c e t y l e n e u n d e r t h e a c t i o n o f WCI6 ( P P A B ) a n d complexes o f A I ( C 2 H s ) 3 with TiCI3 (PPA-3) o r with C o ( A c A c ) 3 ( P P A K ) are e v a l u a t e d b y I R spect r o s c o p y a n d 1H N M R . The methods of purifying the starting materials, determination of the MM of the polymerization products, and also the synthesis of PPAB (A~ ffi2.5 x 104, 2f/'w/2~',= 2'87), and PPAB-3 (2f/'= 2"85 x × 104, .~rw/J~, = 1.62) have been described previously [7]. The Co(AcAc)~, after precipitation from boiling benzene solution in n-heptane had a m.p. of 212-213°C. The compound 1,2,3,4,5-pentaphenylcyclohexa-l,3-diene (V), synthesized by a previously described method [8], had a m.p. of 159-160°C after recrystallization from ethanol. The compound 1,4,5-triphenylcyclohexa-l,3-diene (VI), obtained from diphenylcinnamylphos-¢ phonium bromide and benzylacetophenone, using a previously described method [9], had a m.p. of 132"5-133"5°C, molar extinction in methanol e3so=2.8 × 104 1./mole.era, M=308 (according to mass spectrometry data). The content of ,8-deuterophenylacetylene in the specimen, obtained in accordance with the work of Provder and Jackson [10] was not less than 99~o as judged by IH NMR. data. The products of bulk c0polymerization of phenyl acetylene (145°C, 10 hr) and p-deuterophenylacetylene (160°C, 5 hr) were precipitated into an ampoule swept with argon and sealed under argon, from a 5 ~0 benzene solution in a 10-fold excess by volume of methanol. The PPAT had .AT-/'.= 945, J~rw/AT/,= 1.24, and the PPAB AT/',= 990, 2~'w/2~,= 1.24. Phenylacetylene (5"2 g) was polymerized under the action of AI(C,Hs)3- Co(AcAc)3 as in the synthesis described by Koltsova et ai. [7], at a concentration of monomer, AI(C2Hs)3, and Co(AcAc)~ of 1.82, 5"46 x 10 -2, and-l.82 x 10 -2 mole/l, respectively. The monomer was introduced, and the catalytic complex was decomposed at -90°C, the polymerization temperature was 18°C, and the polymerization time 18 hr. The values of 2~/',and 2~w[2~/',for PPAK were 8500 and 1.88 respectively. The IR spectra were recorded on a Fourier model FTS-150 "Digilab" spectrometer in KBR tablets. A satisfactory signal to noise ratio in the IR spectra was obtained by a large number of scan-

IR spectroscopy and high resolution tH NMR study of PPA microstructures

1541

nings (not less than 200). In treating the spectra with the aid of the Fourier spectrometer computer programs for equalizing of the base line, interpolation, and digital subtraction were used. Before digital subtraction the spectra were normalized, using the integral intensities of a group of bands of C - H stretching vibrations (3000-3150 cm-1) and extra-planar C - H deformational vibrations at 696 c m - t . The 1H NMR spectra were obtained in CDCI3 and CC14 with hexamethyldisiloxane as internal standard, using JEOL C-60-H and "Tesla BS-48-7C" instruments (in the case of V and VI) or "Brucker CXP-200" (in the case of PPA), at frequencies of 60, 80, and 200 MHz respectively.

IR spectra. R e p e a t e d a t t e m p t s are reported in the literature [3, 11-15] to use I R spectroscopy d a t a for e v a l u a t i n g the c o n t e n t of cis- a n d trans-units in the P P A chain. However, so far theoretical analysis o f the I R spectra has n o t been forthcoming. T h e m a i n difficulty in i n t e r p r e t a t i o n of the P P A v i b r a t i o n a l spectra is the resolution of the

TABLE I. BANDS IN THE IR SPECTRA OF PPAT, PDPA AND POLYPENTADEUTEROPHENYLACETYLENi?

C6Hs H t

J

Frequency (cm-1) and I,®~ C6Hs D CoD5 H*

I

I

- ( - C=C),

698 vs 756 s 841 w 872-879 w 910w 1030me 1072mo 1157 w 1180 w 1443 s 1493 s 1600mo 2854 vw 2928 w 3024mo 3055mo 3078w

-

I

-(-c---c-),690 v s 756 s 840 w 914 w 1030 mo 1076 mo 1157 w 1180 w 1443 s 1493 s 1601 mo 2854 vw 2928 w 3024 mo 3055 mo 3078 w

Assignment

-(-c=c-),760 me 840 w 885 w 1030 w 1080 w

Extra-planar def. of C - H (C6H5) Def. C - H (C6Hs) and C - H chain def. Stretching C6H5 - C ? Def. C - H chain Extra-planar def. C - H (C~H2) Stretching C - C chain and planar Def. C - H (C6Hs) Def. C - H (C6H~)

1490 w 1600 mo 2900- 3000 w

Def. C - H (C6H~), stretching C - C (C6H5) Stretching C - C (C6H5) Stretching C - H (impurity)

Stretching C - H (C6Hs) Stretching C - H chain

* Frequencyvaluesof the IR spectra of polypentadcuterophenylaeetyleneare evaluatedfromt h e Simioncscuand Pereec [16]. t vs denotesverystrong,w-weak, me- moderate,s-strong and vw-very weak.

figure

iv the paper by

b a n d s for the v i b r a t i o n s of the b e n z e n e rings a n d the polyene chain. T h e feasibility o reliable identification of the b a n d s is complicated b y the coupling of the polyene chain with phenyl nuclei, which is m a r k e d l y d e p e n d e n t on c o n f o r m a t i o n , in the a b s o r p t i o n b a n d s o f both the m a i n c h a i n a n d the benzene rings. T o o b t a i n reliable selection of a criterion for e v a l u a t i n g the cis-, trans-, a n d cyclohexadiene units in the P P A chain, the P P A spectra o b t a i n e d with various catalysts were analyzed in detail, a n d were c o m p a r e d

1542

M . G . CHAUS~R et al.

with the spectra of low molecular weight compounds containing double bonds, cyclohexadiene fragments, and phenyl rings, and with the spectra of euterated PPA. To separate the absorption bands in the spectra corresponding to C - H vibrations of the phenyl rings and the polymer chain, the spectra of PPAT, PDPA, and polypentadeuterophenylacetylene (Table 1) were compared.

C I

I

I

7"8

I

t

I

7"# v.lO'Zcrn -1

7

5

3 ~,ppm

FIG. 1 FIG. 2 FIo. I. IR absorption spectra of 1 - P P A K , 2 - P P A - 3 , 3 - P P A T , and 4 - P P A B . FIo. 2. NMR spectra of a - P P A T , b - P P A B , and c - P P A K .

Masuda et al. [11] suggested that the ratio of the optical densities of the bands at 870 and 910 cm-x should be used for determining the content of cis- and trans.structures in PPA. As can be seen from Table 1, the band at 910 cm -x does not appear in the spectrum of polypentadeuterophenylacetylene,and consequently cannot be assigned to vibrations of the C - H chain. This conclusion is supported by the presence of this band in the spectra of trans-, trans-l,4-diphenylbuta-l,3.diene and VI, and in the spectra of V, 1,3,5-triphenylbenzene, and pentaphenylbenzene. The use of this ratio for determining the cis- and trans-structures in PPA is thus impossible. Of all the vibration bands, that for the main chain is comparable in intensity with the benzene nucleus bands, and is thus suitable as an analytical band for the extra-planar C - H vibrations at the double bond. According to local symmetry selection rules, this vibration is clearly shown in the PPA spectra with a cis-structure of the units. Evaluation of the content of cis-structure units from the ratio of the intensities of the absorp-

IR spectroscopyand high resolution IH NMR study of PPA microstruetures

1543

tion bands at 760 (deformational C - H vibrations of the benzene ring) and 740 cm-x (extra-planar deformational C - H vibrations of the chain at the double bond) is thus the most reliable method, as proposed by Simionescu et al. [12]. As can be seen from Fig. 1, these bands overlap each other. In view of this, an attempt was made to separate the bands using the least squares method in the approximation of two overlapping curves, each of which is a Lorentz curve [17]. Equalizing of the band base line, separation of the bands, and also minimizing of the deviation of the theoretical curve from the experimental curve was carried out on the Fourier spectrometer computer. It was found that for PPAK D75JD~3~=0"72 for PPA-3 DTsJD737=I.81, and for PPAB DTss/D742 = 15.5. In the PPAT spectrum there was no band at 740 cm-1. Accordingly, the following series of changes in the content of cis linkages is obtained by IR spectroscopy: P P A K > P P A - 3 > P P A B . The other bands used previously for characterizing cis or trans structures in PPA [3, 12-15] are either of weak intensity or do not occur in the spectra. Detailed study of model compounds and various PPA has shown that cyclohexadiene and trans structures in IR spectra do not have bands of characteristic frequency and intensity. 1H N M R spectra. The spectra of the compounds V and VI were obtained in order to assign the signals of the olefin, methylene, and methene protons of the cyclohexadiene structures, which can be realized in PPA chains (fragments of type VII-IX). The t H N M R spectrum of compound V shows non-equivalent geminal methylene protons H6a and H6e; Hto when ~=2.7 ppm (2Jn,.u,,= 15.0 Hz, 3Jut.n, =7.5 Hz), H6~ when ~=3.6 ppm (3JH,,H, ° = 2"0 HZ). It can be concluded from the values of the spin-spin interaction constants for these protons with the methene proton (0= 3.86 ppm) that this is located equatorially. The multiplet of the aromatic protons is in the region 6.5-8.0 ppm. A similar picture is observed in the spectrum of compound VI: H6a-t~= 3.31 ppm (2Ja6°n,. =17.0 Hz, 3JHt.n,°=8.5 Hz, 4Jn,,n2=3"0 Hz), H6e-~=2'81 ppm (3JHt°n, =3.5 Hz), H5~-~=3"98 ppm. The H2 and H3 protons are non-equivalent: H 2 - ~ = 6 " 3 9 ppm (3Jr~n 3= 6"0 Hz), H 3 - ~ = 6 " 6 9 ppm. The multiplet for the aromatic protons in the region = 7 ppm.

R.C~R

H

R

He~ Y V

H

VI

H

"H VII

H

H

R

R VIII

H

H IX

where R = CtHs. The spectra for the different ppm are shown in Fig. 2. In accordance with published information, the signal in the region of 2-4 ppm is assigned to the methine protons of the cyclohexadiene structures (1H, VI), and at 5.82 ppm, to the cis-olefin protons in the linear chain (1H, IH and IV), and to the olefin protons in the cyclohexadiene fragment (2H, VII), and the broad signal in the region of 6-8 ppm to the aromatic (I-IV, VII) and trans-olefin proton (II). According to this assignment, the proportion of cyclo-

1544

M . G . C~AUSBX et al.

hexadiene fragments can be determined from the equation [I8]

683'6 , fCHD= 2~ Ss_9 - 1183. 6

(1)

where fcaD is the proportion of cyclohexadiene fragments in the chain, $3.6 is the area at 3.6 ppm, ZSs_9 is the total of the signal areas in the region of 5-9 ppm. When fCUD is small, and consequently the value of $3.6 is small, in place of the equation proposed by Percec [18] for calculating the proportion of cis-olefin units, it is more correct to use the equation fas=

6Ss.s + 1lfcm) $ 5 l 8 [ 2fCHDE $5-9 ESs_ 9 ,

(2)

where fa. is the proportion of cis-olefin units in the chain, and Ss.s is the signal area at 5.8 ppm. , The spectrum of PPAT (Fig. Paz), which contains a significant proportion of cyclohexadiene structures [5, 6] shows no signal at 5.8 ppm. On the other hand, in cyclohexadiene VI the chemical shift of the cis-olefin protons occurs at 6.39 and 6.69 ppm, i.e. they fall within the range assigned by Percec [18] to absorption of aromatic protons. Assuming that the signal at 5-8 ppm indicates only cis-olefin protons of the linear sections of the polyene chains, 6Ss.s + 12fcm) 85.s

E

+ s36

(3)

Furthermore, the cyclohexadiene fragments can also contain more than one proton but the saturated carbon atom, for example, two methylene (VIII) or two methine (IX). As follows from the spectra V and VI, the methylene and methine protons in the PPA spectra should be found in the region 2--4 ppm. The value offcHo for the cyclohexadiene fragments with two protons of the saturated carbon atom was calculated from the equation fCHD =

683.s 2 )-'.85_9 -- 1183:6

(4)

The error in determiningfcno is fairly high because of the low intensity and considerable breadth of the signal for the aliphatic protons in the region 2--4 ppm. In all eases the values offt,,,, can be found from the equation fn'ans = 1 --feb --fetiD

(5)

As can be seen from Table 2, the change in the content of c/S-unitsin PPA, as found by IH N M R , agrees qualitativelywith the data obtained by IR spectroscopy. Apart from the dependence on the assumptions made, in P P A T there are no linear units containing cis-olefln protons, i.e.there are no cis-cisoidic (III) and cis-transoidic units (IV). In the authors' view, the valuefcm~ =0.24 best reflectsthe real situation.It is ob-

IR spectroscopy and high resolution tH NMR study of PPA microstructures

1545

tained on the assumption that the P P T chain contains a terminal cyclohexadiene fragment (VIII, IX) and is in agreement with the chain termination mechanism in the radical polymerization o f aryl acetylenes b y intramolecular ring closure. TABLE 2. MICROSTRUCTUREOF PPA, AS INDICATEDBY tH NMR Polymer PPAT PPAB

f*n0 0.85 (1) 0.24 (4) 0.09 (1)

PPAK

o.ol (1)

ftrans

0"27 (2) 0"45 (3) 0"66 (2) 0"68 (3)

0"15 0"76 0"64 0"46 0'33 0.31

* The numbers in brackets indicate the equations from which the value o f / w a s calculated. t The value o f f . a , was calculated from eqn. (5) in each case.

The macromolecules obtained by catalytic polymerization o f P P A B and P P A K are constructed on the basis of their linear cis- or trans-units. The special feature of catalytic polymerization o f aryl acetylenes c o m p a r e d with radical polymerization is that the terminal unit o f the growing chain is covalently b o n d e d to the metal catalyst, and chain p r o p a g a t i o n is attained by introduction o f the m o n o m e r molecule at the m e t a l - c a r b o n bond. In this case intramolecular closure c a n n o t give a significant contribution to the chain propagation restriction mechanism, which results in the observed differences in the values offcHu (Table 2).

Translated by N. SIANDEN tREFERENCES 1. M. G. CHAUSER, Yu. M. RODIONOV, V. M. MISIN and M. I. CHERKASHIN, Uspekh khim. 45: 695, 1976 2. B. E. DAVYDOV and B. A. KRENTSEL', Vysokomol. soyed. A2h 963, 1979 (Translated inJ Polymer Sci. U.S.S.R. 21: 5, 1051, 1979) 3. C. I. SIMIONESCU and V. PERCEC, Polymer Sci. Polymer Symp., 67, 43, 1980 4. C, I. SIMIONESCU and V. PERCEC, Progr. Polymer Sci. 8: 133, 1982 5. M. G. CHAUSER, Yu. M. RODIONOV and M. I. CHERKASHIN, Dokl. Akad. Nauk SSSR 230: 1122, 1976 6. M. G. CHASER, Yu. M. RODIONOV and M. I. CHERKASHIN, J. Macromol. Sci. 11:1113, 1977 7. L. S. KOLTSOVA, A. I. KUZAYEV, M. G. CHAUSER and M. I. CHERKASHIN, Vysokomol. soyed. B23: 708, 1981 (Not translated in Polymer Sci. U.S.S.R.) 8. V. S, ABRAMOV and Ts. L. MITROPOLITANSKAYA, Zh. obshch, khim. 10: 207, 1940 9. F. BOLMANN, Chem. Ber. B89: 2191, 1956 10. T. PROVDER and M. T. JACKSON, 6th Intern. Seminar on GPC, Miami Beach, p. 181, 1968 11. T. MASUDA, N. SASAKI and T. HIGASHIMURA, Macromolecules 8: 717, 1975 12. C. L SIMIONESCU, V. PERCEC and S. DUMITRESCU, J. Polymer Sci. Polymer Chem. Ed. 15: 2497, 1977 13.eR. J. KERN, J. Polymer Sci. A-l, 7: 621, 1969

1546

V. S. PSHEZHETSKII and A. V. UDALT$OV

14. Kh. SIMIONESCU, S. DUMITRESCU, I. NEGULESCU, V. PERCHEK, M. GRIGORASH, L DIAKONU, M. LYANKE and L. GORASH, Vysokomol. soyed. AI6: 790, 1974 (Translated in Polymer Sci. U.S.S.R. 16: 4, 911, 1974) 15. A. A. BERLIN and M. I. CHERKASHIN, VysokomoL soyed. A13: 2292, 1971 (Translated in Polymer Sci. U.S.S.R. 13: 10, 2581, 1971) 16. S. I. SIMIONESCU and V. PERCEC, Polymer Sci. Polymer Letters 17: 421, 1979 17. Primenenie spcktroskopii v khimii (Use of Spectroscopy in Chemistry). p. 298, Moscow, 1959 18. V. PERCEC, Polymer Bull. 10: 1, 1983

Polymer Science U.S.S.R. Vol. 30, No. 7, pp. 1546.-1S53, 1988 Printed in Poland

0032-3950]88 $10.00+ .00 O 1989 Pergamon Press plc

EFFECT OF MODIFYING POLYMETHACRYLIC ACID COVALENTLY BONDED TO PORPHYRIN ON ITS ACID-BASE PROPERTIES* V. S. PSHEZHETSKII and A. V. UDALT$OV M. V. Lomonosov State University,Moscow (Received 6 February 1987) Tctra(p-aminophcnyl) porphyrin was immobilized on PMAA and PMAA modified with cetylamine (PMAA-cetyl) and the effect of microcnvironment on the acid base proporties of the bound porphyrin was studied. The pK, of porphyrin immobilized on PMAA was increased to 7-9, while PMAA-cetyi was decreased to 0.8 compared with the pK---4 values for tetraphenyl porphyrin. The effects obtained are associated with the effect of the electrostatic field on the macro-ion and the hydrophobic microenvionment of porphyrin in the first and second systems respectively.

OF TH~ various models of t h e primary photosynthesis processes, important results on the stabilization of separated charges have been obtained recently with water soluble porphyrins containing ionogenic groups, and especiallypositivelycharged Zn porphyrins [1-3]. Data are available on the use of polyelectrolytesfor stabilizingseparated charges by interaction with the electrostaticfieldin macro-ions. However, these problems have been inadequately developed in polymer systems [4-6]. It must be expected that the immobilization of porphyrins on polymerization would lead to change in a number of properties of these macrocyclic molecules. In particular, in ionogenic water soluble polymers containing hydrophobic regions a change in the acid-base properties of the porphyrin is possible, as in the change in two-three orders of magnitude of the aliphatic amino groups in aqueous solution when these are immobilized in the hydrophobic regions of polymer molecules [7].

* Vysokomol. soyed. A30: No. 7, 1470-1475, 1988.