J. Am. Chem. Soc. 1994,116.5519-5520
5519
Recognition of Dyes by KISOl Crystals: Choosing Organic Guests for Simple Salts Michael P. Kelley, Bart Janssens, a n d Bart Kahr'
Department of Chemistry, Purdue University Wesf Lafayette, Indiana 47907-1393 William M. Vetter
Deparfment of Materials Science State University of New York Stony Brook. New York 1 1 794-2275
Figure 1. Photographof KSOIcrystalscontaining Ic(left) and2 (right). I
I
Received January 19, 1994 Organisms use matricesoforganic macromolecules tocatalyze inorganic crystal growth thereby constructing teeth, shells, bones, andbeah.' Chemists alsohavebeenuniting inorganicandorganic materials. Zeolites, clays, a n d sol-gel glasses serve a s vessels for a variety of organic transformations.2 Organic hourglass inclusions (HIS) are simple ionic salts containing oriented dyes. First describedin 1854,"Isweremostintensivelystudiedinthe 1 9 3 0 ~ . ~ They were abandoned as curiosities before their structures were determined.' Here, we propose a model for the inclusion of triarylmethane dyes in K2.304 that is consistent with polarized absorption spectroscopy. W e used this structure a s the basis for the rational design of a n H I with prescribed optical properties. Themost appealinghistorical HI,K2S04stainedbyacidfuchsin (la, Scheme I), was discovered by Buckley.4a W a t e r solutions (2.0 X 1V M l a , lb, or IC a n d 5.0 X IW M K2SOI) were evaporated at room temperature; they depwited well-formed crystals6withdichroicfuchsiacoloringinthe11 10}7growthsectors (Figure 1). W e determined that there is 1 dye molecule for IO3 unit cells in a substituted sector by quantifying the absorbance of dissolved crystals. Structures like 1 have two distinct diastereomeric propeller conformations. Inthesymmetrical conformer (S) threesulfonates point to t h e s a m e side of t h e mean molecular plane while the asymmetrical conformer (A) displays two u p and onedown (Figure 2 ) . Their geometries, when associated with three K+ ions, were calculated using the A M I Hamiltonian?
r=6.6A.y-7.3A.i=io2A
z;s.sA,r=?.sA,r;s.5A
z=s..rA.yi1.76.~=9.sA
la WO. a Figure 2. Left: AMI geometry of 11 in the A conformation. Center: K~SO~latticefora(l10)growthsectorviewedalong [OIO].Right: AMI geometry of 2. Sulfonate S a t o m are filled. The sulfate triangle in the K ~ S Olattice I whichserves as thesiteofattachment for 1and2is indicated in this way. Relevant triangles, drawn in fine line, are viewed in a perpendiculardirection. INDO/S calculated transition dipolesaremarked on the molecules (- for 1 and - - - for 2). Their cxpcrirnental counterparts. measured through polarized absorption spectroscopy, are indicated on the K2S0, lattice. Blue-shifted (B) and red-shifted (R) transitions for 1s are labeled. We cannot distinguish between symmetryrelated sulfate triangles. Lengths (A) of the legs ( x . y. z ) of the sulfur triangles are listed below each drawing.
Scheme 1
(1) Mann, S.;Archihald. D. D.;Didymus, 1. M.; Douglas, T.; Hcywmd, B. R.; Mcldrum, F. C.; Reeves, N. J. Science 1993.261. 1286. Addadi, L: Weiner, S. Angou. Chem.. Int. Ed. Engl. 1992, 31, 153. (2) Izumi. Y.; Urabe. K.; Makoto. 0.Zeolite. Clay. and Hereropoly Acid in Organic Reoniom; VCH New York, 1992. Klein, L. C. Sol-Gel Opricr Processing and Applicationr; Kluwcr: Dordrecht, 1993. Ramamurthy, V., Ed. Photoehrmirtry in Orgmiredond ConstrainedMedio; VCH New York, 1991.Sccalso: Kirkar,E.S.;David, D.E.; Michl, J. J Am. Chem. Soc. 1990, 112, 139. Mttehcr, H.; Hertz. 0.; Fox, M. A. Chem. Phys. Lctt. 1989, 160, 121.
1854. 167. 491 (3) de SCnarmont. H Ann Phyr LPJPZIBI Buck1q.H C Cryrfol (4) (a)Bucklc).H E Z K~irfoii~,gr.1934.8~.248 Growth. John Wile,: New York. 1951: DD 317-378 Ihl Pan XI1 trance. W.F.; Wolfc, K. M. 3. Am. Chim. SG.'l941,63. I505 ( 5 ) For some ~tructuralinferences. see: Neuhaus. A. Angew. Chem. 1941,
We measured the polarized visible absorption spectra of oriented l/K2S04 crystals (Figure 3).9 T h e broad bands in t h e visible region were fitted as the s u m of two Gaussian functions with a separation varying between 35 a n d 40 n m for different crystal orientations. From t h e ratios of integrated intensities of the
54,521.Slavnova,E.N. C,owthofC~yryaols;CansultantsBurcau: NewYork,
1958: pp 111-125. Hartmann. H. Zur Physik und Chemie der Krismllphosphore; Akadcmie-Verlag: Berlin, 1960: p 136 (6) X-ray topographicstudiesindicate that Hls an excellent 'single crystals" of K2S04and argue against dye aggregation.Dudley, M.; Vetter, W.; Kahr, B. In Nalional Synchrotron Light Source Report: Hurlburt, S. L., Lazarz, M. L., Eda.; Brookhaven National Labaratary: Uptan, New York, 1993; in
transitions for spectra with light incident i n and polarized along the principal directions, we determined the transition moments for the guest in the crystal.1° Using t h e INDOIS method" we
press. Thegrawthofthesccrystalswasdeseribedasanexperimentforstudcnts. Kahr, B.; Chow, J. K.; Peterson, M. 1.Chem. Educ.. in press. (7) 1" order to be consistent with Buckley, Miller indices refer to ratios determined bv classical eaniometrv: a = 5.772 A. b = 10.012 A. c = 7.483 A far Pmm \o 62. Sei \'on (iroth. P. C'hrmcrrhr Kqrfollugrophir.c 2. WilhclmEngclrnann Leipng. 1908,p311. Wychoff.R G Cqnol.Slrwrvrer
