Langmuir 1994,10, 1517-1523
1517
Synthesis, Location, and Photoinduced Transformation of Zeolite-EncagedThioindigo Rainer Hoppe,la Gunter Schulz-Ekloff,*Ja Dieter W o h r l e , l b Christine Kirschhock,lCand Hartmut Fuesslc Institutes of Applied and Physical Chemistry and of Organic and Macromolecular Chemistry, University of Bremen, Postfach 330440, 0-28334 Bremen, Germany, and the Institute of Structural Research of the Department of Material Science, Technical University of Darmstadt, Petersenstrasse 20, 0-64287 Darmstadt, Germany Received February 1 1 , 1994@ NaX-encaged thioindigo was prepared either by incorporation of the dye during hydrothermal crystallizationof the zeoliteor by solid-statereaction between dehydrated NaX and dye. Rietveld refinement of X-ray diffraction patterns revealed the location of the dye moleculesat the 12-memberedrings connecting two neighbored supercagesof the faujasite structure. Depending on the preparation conditions, the sodium cations in closest vicinity to the dye molecules populate (1)SIIsites, (2) SIPsites, or (3) SIIIsites. The photoinduced trans-to-cisisomerizationas well as the oppositethermal cis-to-transconversion was followed by visible spectroscopy. No photoisomerization was observed for samples exhibiting Na+ in SIpaorSIII cation sites,thus blockingthe torsional motion. The analysis of the kinetics of the cis-to-transisomerization in a sample with Na+ in SIIexhibited an increased energy barrier for the twisting mode of approximately 4 kJ mol-' as compared to thioindigo in solution. Decreased rates of photodegradation for the encaged dye in comparison with the dissolved one were observed. The development of materials with advanced photochemical and photophysical properties is demanded from the increasing application of light in the fields of information transfer, processing, and storage. Dye molecules, which have found broad application in the generation of coherent light of high intensity,Zcan exhibit bistable states for optical switching and information storage3 or hyperpolarizabilities for various kinds of nonlinear optical pro~esses.~ Organized anchoring of dye molecules in the host matrix of molecular sievesenables the use of collective properties of the dye assemblies due to the vectorial addition of the individual molecular behavior in a geometrically constrained encapsulated state, e.g., for the generation of laser light of doubled f r e q ~ e n c y .Various ~ potential applications for molecular sieve-anchored dyes are proposed, e.g., as dye pigments6 or for high-density optical data storage via persistent spectral hole-burning.' The photoinduced isomerization of thioindigoid dyes was Abstract published in Advance ACS Abstracts, April 1, 1994. (1)(a) Institute of Applied and Physical Chemistry, University of Bremen. (b) Institute of Organic and Macromolecular Chemistry, University of Bremen. (c) Institute of Structural Research of the Department of Material Science, Technical University of Darmstadt. (2)Nair, L. G. Prog. Quantum Electron. 1982,7, 153. (3)(a) Kuder, J. E.J . Imaging Sci. 1988,32,51. (b) Tomlinson, W. J. Appl. Opt. 1984,23,4609.(c) Friedrich, J.; Haarer, D. Angew. Chem., Int. Ed. Engl. 1984,23,113.(d) Moerner, W. E., Ed. Persistent Spectral Hole Burning: Science and Applications; Topics in Current Physics; Springer: New York, 1988. (4)(a) Chemla, D. S., Zyss, J., Eds. Nonlinear Optical Properties of Organic Molecules and Crystals; Academic Press: New York, 1987.(b) Zyss, J. Nonlinear Opt. 1991, 1, 3. (5)(a) Cox,S.D.; Gier, T. E.; Stucky, G. D. Chem. Mater. 1990,2,609. (b) Caro, J.; Finger, G.; Richter-Mendau, J.; Werner, L.; Zibrowius, B. @
Adu. Mater. 1992,4,273. (6)(a) Balkus, J. J.; Kowalak, 5.;Ly, K. T.; Hargis, D. C. In Zeolite Chemistry and Catalysis; Jacobs, P. A., Jaeger, N. I., Kubelkova, L., Wichterlova, B., Eds.; Elsevier: Amsterdam, 1991;Stud. Surf. Sci. Catal. 1991,69,93.(b)Hoppe,R.; Schulz-Ekloff,G.;Wbhrle,D.DE41 26 461 A l . (7)(a) Hoppe, R.; Schulz-Ekloff, G.; WBhrle, D.; Ehrl, M.; Briuchle, C. In Zeolite Chemistry and Catalysis; Jacobs, P. A., Jaeger, N. I., Kubelkova, L., Wichterlova, B., Eds.; Elsevier: Amsterdam, 1991;Stud. Surf. Sci. Catal. 1991,69,199. (b) Deeg,F. W.; Ehrl, M.; Briuchle, C.; Hoppe, R.; Schulz-Ekloff, G.; Wbhrle, D. J . Lumin. 1992,53, 219. (c) Ehrl, M.; Deeg, F. W.; Brguchle, C.; Franke, 0.; Sobbi, A.; Schulz-Ekloff, G.; Wbhrle, D. J . Phys. Chem. 1994,98,47.
0743-7463/94/2410-1517$04.50/0
the subject of various investigations? also with respect to potential applications for optical recording.9 In general, intrazeolite chemistry is characterized by (i) geometrical constraints being the reason for transitionstate selectivitieslOand (ii) peculiar interactions, e.g., with cations, causing symmetry changesll and various alterations of photophysical and photochemical properties.12 It has been demonstrated that cationic dye molecules can be incorporated in the channels and cages of molecular sieves as singular molecules either by ion exchange or by encapsulation during hydrothermal crystallization, resulting in loadings of up to one dye molecule per unit ~ e l l . ~ ~ J ~ Another route for the incorporation of dye molecules in molecular sieves is the synthesis of the chromatogene in the cages of a faujasite host from precursor m01ecules.l~ Up to now, the precise localization of dye molecules in the voids of molecular sieves and the consequences of a defined host-guest interaction for photochemical behavior have not yet been elucidated. In the following, the location of (8)(a) Haucke, G.; Paetzold, R. Nova Acta Leopold., Suppl. 1978, suppl. 11. (b) Breuer, H. D.; Jacob, H. Chem. Phys. Lett. 1980,73,172. (c)Wyman, G. M.; Wallace, B. R. J . Am. Chem. SOC.1951,73,1487,4267. (9)(a) Klages, C. P.; Kobs, K.; Memming, R. Ber. Bunsen-Ges. Phys. Chem. 1982,86,716. (b) Takahashi, T.; Taniguchi, Y.; Umetani, K.; Yokouchi,H.; Hashimoto, M.; Kano, T. Jpn. J . Appl. .. Phys., Part 1 1985, 24 (2),173. (10)Csicsery, S. M.Zeolites 1984,4, 202. (11) (a) Bein. T.: McLain. S. J.: Corbin. D. R.: Farlee. R. D.: Moller. K.;'Stucky, G. D.; Woolery, G.; Sayers, D. J. Am.'Chem..Soc.1988,110; 1801. (b) Hong, S.B.; Cho, M. M.; Davis, M. E. J.Phys. Chem. 1993,97, 1622. (12)(a) Ramamurthy, V.; Eaton, D. F.; Caspar, J. V. Acc. Chem. Res. 1992,25,299. (b) Ramamurthy, V., Ed. Photochemistry in Organized and Constrained Media; VCH Weinheim, 1991. (c) Turro, N. J.; Wan, P. J. J . Am. Chem.SOC.1985,107,678.(d)Garcia-Garibay, M. A,; Zhang, Z.; Turro, N. J. J . Am. Chem. SOC.1991,113,6212. (13)(a) Wohlrab, S.;Hoppe, R.; Schulz-Ekloff, G.; WBhrle,D. Zeolites 1992,12,862.(b) Hoppe, R.;Schulz-Ekloff, G.; Wbhrle, D.; Shpiro, E. S.; Tkachenko, 0. P. Zeolites 1993,13, 222. (c) Calzaferri, G.; Gfeller, N. J. Phys. Chem. 1992,95,3428. (14)(a) Romanovsky, B. V. Proceedings of the 8th Znternutional Congress on Catalysis; Verlag Chemie: Weinheim, 1984; Vol. 4,p 657. (b)Meyer, G.; Wbhrle, D.; Mohl, M.; Schulz-Ekloff, G. Zeolites 1984,4, 30. (c) Herron, N.; Stucky, G. D.; Tolman, C. A. J. Chem. SOC.,Chem. Commun. 1986,1521. (d) Parton, R. F.; Uytterhoeven, L.; Jacobs, P. A. InHeterogeneous Catalysis and Fine Chemicalsll; Guisnet, M., Barrault, J., Bouchoule, C., Duprez, D., PBrot, G., Maurel, R., Montassier, C., Eds.; Elsevier: Amsterdam, 1991;Stud. Surf.Sei. Catal. 59,395.
0 1994 American Chemical Society
1518 Langmuir, Vol. 10, No. 5, 1994
Hoppe et al.
Table 1. Sample Preparations, Absorption Maxima (nm), Dye Offers (mol of dye/g of NaX),and Dye Uptake (molecules of dye per unit cell or percentage of offered amounts)
no. 1 2 3 4
5 6
sample preparation incorporation by template synthesis, dried in air incorporation by template synthesis dried 2 h, 350 K incorporation by template synthesis, dried 12 h, 350 K incorporation by solid-state reaction incorporation by solid-state reaction adsorption on the surface from solution
70
a
absorption (nm)
dye offer (mol&)
dye uptake (molecules of TI per unit cell)
535 535
5X1V 5X10-6 5 X l P 4X1W 9X1W 1.2 x 10-6
0.4 0.4 0.4 0.7 1.4 0.02
560 535 562 550 540
dye uptake (%) 62 62 62 13 11 12
Reference sample: TI dissolved in toluene (106 moledmq).
0'
2 nm) were present (Figure 2; cf. Experimental Section). The dye content amounts to approximately 1T I molecule per 2 unit cells or per 16 supercages, respectively, obtained from photometry (Table 1, samples 1-3). Higher dye content is achieved by loading dehydrated NaX with TI in a solidstate reaction, resulting in occupations of ca. one T I molecule per unit cell (Table 1, samples 4 and 5). Location of Thioindigo in NaX. The X-ray powder diffractogram (Figure 3A) exhibits the known peak positions of NaX.'6 No reflections for solid TI" are observed. The patterns are analyzed by means of Rietveld refinement (15) (a)Hoppe,R.; Schulz-Ekloff,G.; W6hrle, D.; Rathousky,J.;Starek, J.; Zukal, A. Zeolites 1994, 14, 126. (b) Desmond, M. J. US 4 582 693, 1986. (16) Ballmoos, R., Higgins, J. B., Eds. Collection of simulated X R D powder patterns for zeolites; Zeolites 10 ( 5 ) ;Butterworth-Heinemann: Stoneham, MA, 1990.
(17) Hoppe, R. Ph.D. Thesis, University Bremen, Germany, 1992.
50
100
150
200
2 50
P (ma H9)
Figure 2. Adsorption and desorption isotherms of cyclopentane on (1)dye-free and (2) dye-loaded zeolite NaX.
I
10
II
I I
I !
Ill IIIII I / i I I I I I I I I 1 I I l IllillllliillllilllIIIIIIIIIIII11111
20
-
40
30
50
60
2s
Figure 3. XRD pattern of (A) faujasite NaX containing thioindigo (sample 1) combined with (B)the deviation between Rietveld refinement and measurement.
in combination with electron density difference mapping.ls The fitting procedure acts with the parameter values for the host lattice as well as the cations and water molecules given by Olson.lS The cation position in the center of a double six-membered ring, denoted as the SI site (Figure 420),is chosen as the origin of coordinates. The center of the T I molecule is placed in the center of a 12-memberedring window connecting two neighboring supercages (Figure 5). This arrangement enables the closest approach of the donating S and 0 atoms of the dye molecule to an accepting cation position in a supercage, i.e., a Sn, SI^, or SVsite. The bond lengths and bonding angles of TI are constrained to average values of 0.14 nm and 120° in the six-membered rings and 108O in the five-membered rings. The temperature factors of all atoms are assumed to be equal. (18)Rietveld, H.M.J. Appl. Crystallogr. 1969,2, 65.
(19) Olson, D.H. J. Phys. Chem. 1970, 74,2758. (20) Smith, J. V. Ado. Chem. Ser. 1971, 101, 171.
Zeolite-Encaged Thioindigo
W Figure 4. Cation positions in a faujasite structure.m
A
Langmuir, Vol. 10, No. 5, 1994 1519
Table 2. Crystallographic Data of Sample 1 Containing Cis and Trans Isomers of Thioindigo (Space Group Fd3, Dimension of the Unit Cell 8 = 24.97 A) mean square occupation fractional coordinates displacement atom factor X Y .2 (A? T1 1.00 -0.050(0) 0.128(1) 0.040(7) 0.15 T2 1.00 -0.055(7) 0.030(9) 0.127(1) 0.15 01 1.00 -0.112(3) -0.000(4) 0.113(0) 0.26 1.00 -0.002(3) -0.000(7) 0.149(4) 02 0.26 1.00 -0.029(3) 0.066(4) 0.078(8) 03 0.27 04 1.00 -0.075(0) 0.065(0) 0.174(9) 0.29 Nal 1.00 O.oo00 O.oo00 O.oo00 0.33 0.233(9) 0.233(9) 0.233(9) 0.53 Na2 0.30 0.289(2) 0.362(5) 0.179(4) 0.60 Na3 0.49 ow1 0.63 0.074(1) 0.074(1) 0.074(1) 0.21 0.51 ow2 0.701(7) 1. 0.701(7) 0.701(7) 0.48 c1 0.44 0.019(3) 0.500(0) 0.019(3) 0.18 0.44 0.012(1) 0.500(0) 0.076(6) s1 0.09" 0.44 0.062(9) 0.500(0) 0.104(0) c2 0.18 0.44 0.075(8) 0.500(0) 0.159(7) c3 0.18 0.132(2) 0.500(0) 0.173(3) c4 0.18 0.44 0.44 0.173(3) 0.500(0) 0.132(2) c5 0.18 0.44 0.159(7) 0.500(0) 0.075(8) C6 0.18 0.104(0) 0.500(0) 0.062(9) 0.18 0.44 c7 0.44 0.076(6) 0.500(0) 0.012(1) C8 0.09 0.44 0.104(8) 0.500(0) -0.036(3) oc1 0.09 0.012(1) 0.500(0) 0.076(6) 0.09 0.44 c9 0.09 0.44 -0.036(3) 0.500(0) 0.104(8) oc2 0.44 -0.076(6) 0.500(0) 0.012(1) s2 0.09 a An occupation factor of 1 for incorporated TI is equivalent to one dye molecule per supercage.
B
C
Figure 5. Location of trans-thioindigo (A, C) and cis-thioindigo (B) in the center of a 12-membered ring connecting two supercages. Black dots (C) mark the sodium cation positions (Sn. sites) for sample 2.
For sample 1, characterized by a mild removal of the solvent molecules, the Rietveld refinement resulted in coordinates for the zeolite framework atoms, the cations, and water molecules presented in Table 2. The occupation factors, exhibiting values
