STRUCTURAL STUDIES OF SOME NATURAL PRODUCTS FROM KAEMPFERIA PARVIFLORA, IRIS GERMANICA LINN. AND ANDROGRAPHIS PANICULATA NEES

Presenter	:	JEANNIE TEH BEE JAN
E-mail	:	-
Date	:	26 / 7 / 2007
Time	:	10.00 AM
Venue	:	(CEMACS) CONFERENCE ROOM, SCHOOL OF PHYSICS
Sypnosis	:	In this research, single crystal x-ray crystallography method had been used to determine the crystal structures of five natural products. The data was collected using the APEX-2 CCD diffractometer (Bruker, 2005). Low temperature data were collected using the Oxford Cryosystem Cobra low-temperature attachment. The structures were then solved and refined by the use of SHELXTL (Sheldrick, 1998) software. This software also allows us to see the arrangement of molecules in the crystal and the packing interactions involved. Details of the solved structures are given below:- The structure of 3,5,7 – Trimethoxy – 2 – phenyl - 4H – 1 – benzopyran - 4 – one crystallizes in the space group of P21/c. The crystal structure is stabilized by p-p interactions between the benzopyran – 4 - one ring systems of inversion-related molecules which were stacked along the a-axis. C-H…O interactions further stabilized the crystal packing. The structure of 5 – Hydroxy – 7 – methoxy – 2 - (4 - methoxyphenyl) - 4H – 1 – benzopyran – 4 – one crystallizes in the P21/c space group. The benzopyran - 4 - one ring system and the methoxyphenyl substituent are approximately coplanar. The molecules are linked via intermolecular C-H…O hydrogen bonds to form chains along the a–axis. The structure of 5,7 – Dimethoxy – 2 – phenyl - 4H – 1 – benzopyran – 4 - one chloroform solvate is stabilized by p-p interactions between the benzopyran - 4 - one ring systems of inversion-related molecules which were stacked along the c-axis. C-H…O and C-H…p interactions further stabilized the crystal packing. The crystal has a space group of P21/c. The compound of 4’ – Hydroxy – 5 – methoxy - 6,7 – methylenedioxyisoflavone forms an infinite one-dimensional zigzag-like chain developing parallel to b axis through O-H…O hydrogen bonds. The chains are stacked along the c-axis. The crystal structure is further stabilized by weak p-p and C-H…p interactions. The compound crystallizes out in the space group P21/c. The compound of 14 – Deoxy - 11,12 – didehydro - 3,19 –isopropylideneandrographolide crystallizes out in the space group of P212121. All the six-membered rings in the structure adopt chair comformations. The crystal structure is stabilized by C-H…O interactions, which form a two-dimensional network parallel to ab plane.

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