Pyrene crystal structure

The results of a crystal structure formed by a trans opening of the BPDE l(+) to yield 7,8,9,10-tetrahydroxy-7,8,9,10-tetrahydro-benzo[a]pyrene (BPTOH) shows a Cde (90) conformation of the ring. The 07-HOT and O8-H8 groups are de, and the 09-H9 and 010-H10 are also de. The torsion angles of the benzo ring are in best agreement with our second most stable structure, Cde, of the anti BDE-N2(G) trans adduct as is seen from Table III. In adduct formation to N2(G) the trans adduct is the major product (13-22) ... 

The only purine-aromatic complex crystal structure published thus far is the tetramethyluric acid-pyrene structure (6). The orientation of the molecules in this complex is shown below in VIII. 

Fig. 21 Crystal structure of the charge-transfer complex pyrene pyromellitic dianhydride (PMDA). The alternate stacking of donors and acceptors. .. DADADA. .. is characteristic of weak charge-transfer complexes. (After Boeyens and Herbstein, 1965b)...

These systems exhibit considerable affinity for halide anions. X-ray analysis ascertained the formation of an anionic 2 1 chloride adduct of (1) where the chloride is simultaneously bound by four mercury atoms. In the crystal structures of (2) Cl and (2) l2, the anions are located within the macrocycle and complexed cooperatively by the four mercury(II) centers. Several anionic complexes of (3), including bromide, iodide, and thiocyanide salts, have been isolated. The compounds adopt multidecker stmctures with the hexacoordinated anions effectively sandwiched between two successive molecules of (3). The Lewis acidity of perfluoro-ortAo-phenylenemercury (3) has also been substantiated by its ability to form stable adducts with neutral substrates (HMPA, DMSO, ethyl acetate, and acetonitrile) and arenes. The (3) -CeHe adduct exists as extended stacks of nearly parallel, staggered molecules of (3), which sandwich benzene molecules. Similar structures have been reported for the corresponding adducts with biphenyl, naphthalene, pyrene, and triphenylene. 

Fig 5. Crystal structure of the radical salt pyrene (117)Na" " yielding a zigzag structure with solvent molecules... 

A 3.1 A crystal structure of human topoisomerase I in complex with DNA containing 8-oxo-dG at the +1 position in the scissile strand shows the enzyme active site to be rearranged into an inactive conformation." A primer-template duplex in complex with the lesion-bypass polymerase Dpo4 is studied in which there is a benzo[a]pyrene diol epoxide adduct of dA (183) base paired with thymidine in the enzyme active site. Two conformations of the adduct are observed, one in which it is intercalated between base pairs, and the other in... 

FIGURE 15.12 (cont d). (b) Crystal structure of 1,3,7,9-tetramethyluric acid and pyrene, (c) HOMO/LUMO overlaps for PAH-TNB complexes. Shown are signs of the wave functions (not electronic charge) for the HOMO and LUMO, and the overlap of molecules observed in the crystalline state (as predicted from the HOMO/LUMO overlap of positive with positive wave functions). 

Damiani, A, De Sanctis, P., Giglio, E., Liquori, A. M., Puliti, R., and Ripamonti, A. The crystal structure of the 1 1 molecular complex between 1,3,7,9-tetra-methyluric acid and pyrene. Acta Cryst. 19, 340-348 (1965). 

Figure 10.48 (a) Space-filling view of the structure of the snub cube (f) formed from six [4]resorcarenes and eight water molecules. (b) Crystal structure of the analogous pyrogaUol[4]arene hexameric capsule containing two molecules of pyrene butyric acid (reproduced with permission from [54]). 

Ling, H., Sayer, J.M., Plosky, B.S., Yagi, H., Boudsocq, F., Woodgate, R., Jerina, D.M., and Yang, W. (2004) Crystal structure of a benzo[a]pyrene diol epoxide adduct in a ternary complex with a DNA polymerase. Proc. Natl. Acad. Sci. USA, 101, 2265-2269. 

FIGURE 1. Geometry of a pair of pyrene molecules in the crystal. [Based on the crystal structure by Von Allman, Z. Krist., 123, 129 (1970).]... 

There are also crystals of aromatic hydrocarbons whose fluorescence is an excimer emission. For this to occur, the molecules in the crystal must be ordered pairwise in parallel planes, with a small distance between neighbouring planes. In the pyrene crystal, this distance is 3.53 A. The molecules are thus already ordered as physical sandwich dimers within the crystal. Prime examples of this - as also in solution - are pyrene and perylene (cf the crystal structures in Chap. 2, Figs. 2.11 and 2.12). 

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