Associate Professor LAI Yee Hing
B.Sc., 1976, Nanyang University; Ph. D., 1980, University of Victoria; Post-doctoral Fellow, 1980-2, University of California at Berkeley and Lawrence Berkeley Laboratory
| Department of Chemistry, NUS
3 Science Drive 3
| Office: S9-05-10
Our research interests are centred mainly on the studies of conjugated aromatic systems going from theoretically interesting molecules to organic materials for specific applications. A separate effort focuses on the investigation of selected Chinese medicinal plants.
The annulene 1
has been used as a probe to study the various annelation and conjugation effects on its diatropicity. Experimentally measurable chemical shifts have been correlated with theoretically calculated bond orders and resonance energies. 3
, for example, is a novel model shown to completely nullify the ring current in1
through annelation. Ring current shielding effect of 1
was found to extend to about 14 Ã… above the mean molecular plane in model 4
Collaborative work with materials scientists involves the synthesis of a series of conjugated polymers, which exhibit tuneable photoluminescence, by linking alternatively oxadiazole, carbazole, thiophene and/or benzene derivatives. Silicon-containing PPV and related alternating copolymers have also been shown to be promising green and green-blue emissive materials for light-emitting device application.
ollaborative work with surface scientists covers the investigation of chemisorption of aromatic and conjugated molecules on silicon surfaces. Benzene and several heteroaromatic systems, for example, have been found to bind to adjacent adatom and rest atom on the Si(111)-7x7 surface throughs bonds. Extension of this work may lead to modified silicon surfaces with chemically bonded functions and/or unique organic synthesis on active surfaces.
A focused collaborative effort with a medical team has been directed to the isolation of bioactive compound(s) from a Chinese medicinal plant proven to exhibit immuno-suppressive properties.
- Y. Cao, K. S. Yong, Z. Q. Wang, W. S. Chin, Y. H. Lai, J. F. Deng and G. Q. Xu. Dry Thienylation of the Silicon (111)-(7 X 7) Surface. J. Am. Chem. Soc., 122, 1812-1813 (2000).
- W. Huang, H. Meng, W.-L. Yu, J. Pei, Z. K. Chen and Y.-H. Lai. A Novel Series Of p-n Diblock Light-Emitting Copolymers Based On Oligothiophenes And 1,4-Bis(Oxadiazolyl)-2,5-Dialkyloxybenzene. Macromolecules, 32, 118-126 (1999).
- Y. Cao, X. M. Wei, W. S. Chin, Y.-H. Lai, J. F. Deng, S. L. Bernasek and G. Q. Xu. Formation of Di-Sigma Bond in Benzene Chemisorption on Si(111)-7x7. J. Phys. Chem. B, 103, 5698-5702 (1999).
- Yap, H. K., X. J. Zuo, M. Toyoda, Y. Okada, S. G. Ang, Y.-H. Lai, J. M. Matloff, A. Marchevsky, V. S. Ramgolam and S. C. Jordan. Immunosuppressive Effect of the Hydrophobic Extract of a Chinese Herb On Rat Lung Allograft Rejection. Transplant. Proc., 30, 980-981 (1998).
- Y.-H. Lai and P. Chen. Synthesis and Diatropicity of Trans-10b,10c-dimethylacenaphthyleno(1,2-e)-10b, 10c-Dihydropyrene: A Model Aromatic Molecule to Verify the Effect on Conjugation on the Diatropicity of an Annulene. J. Org. Chem., 62, 916-924