Windward Community College


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Chem 152
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Instructor Information
Core Page

Leticia U. Colmenares     


University of Hawaii, Chemistry, Ph.D.,1991

University of the Philippines, Chemistry, M.S.,1982  

Mindanao State University, Chemistry, B.S.,1975 (magna cum laude)


            Instructor in Chemistry, University of Hawaii-Windward (8/1/99-present)

            Faculty Coordinator, WCC Marine Option Program (7/01-6/03)

            Research Associate, University of Hawaii-Manoa (Summer, 2002, 2001 and 2000)


Liu, Robert S. H. and Colmenares, Leticia U. , " The Molecular Basis for the High Photosensitivity of Rhodopsin", Proc. Natl. Acad. Sci. USA, 100, 25, 14639-14644 (2003).

Colmenares, L. U. and Liu, R.S.H., "Regiospecific Protein perturbation on F NMR Shifts and Photoisomerization of Fluororhodopsins. An Interpretation Based on Recenet Crystal Strucures of Rhodopsin," J. Photosci., Vol. 10, 81-87 (2003).

Colmenares, L. U., Asato, A. E. and Liu, R. S. H., "Effects of Fluoro-substituents on Excited State Properties of Conjugated Polyenes (Fluorinated Retinoids)", The Spectrum, 14, 3, 8-11 (2001).

Ni, J., Liu, J., Colmenares, L.U. and Liu, R. S. H., "Isomers of 10-Fluoro-20-13C-retinal and the Corresponding Rhodopsin Analogs," Tet. Lett., 42,1643-1644 (2001).

Colmenares, L. U., Zou, X., Liu, J., Asato, A. E., Liu, R. S. H., de Lera, A. R. and Alvarez, R., "11,12-Difluororhodopsin and Related Odd-Numbered Fluororhodopsins.  The Use of JF,F for Following a Cis-Trans Isomerization Process," J. Am. Chem. Soc., 121, 24, 5803-5804 (1999).

Hoischen, D., Colmenares, L. U., Koukhareva, I., Ho, M. and Liu, R. S. H., "9-CF3 and 13-CF3-b-Carotene,canthaxanthin and related carotenoids.  Synthesis, characterization and electrochemical data," J. Fluor. Chem., 97,165-171 (1999).

Imai, H., Hirano, T., Terakita, A., Shichida, Y., Muthyala, R. S., Chen, R., Colmenares, L. U., and Liu, R. S. H., “Probing for the Threshold Energy for Visual Transduction: Red-Shifted Visual Pigment Analogs from 3-Methoxy-3-Dehydroretinal and Related Compounds,” Photochem. Photobiol., 70, 111-115 (1999).

Iwasa, T.,  Colmenares, L. U., Hirata, K., Arime, Y., Nakagawa, M., Kikkawa, S., Takashima, H., Nosaka, A.,Naito, A., Liu, R. S. H. and Tsuda, M., "19F NMR and UV-Vis Absorption Spectroscopic Studies of Fluorinated Octopus Rhodopsin and its Photoproducts, J. Phys. Chem. A,102, 5602-10 (1998).

Hoischen, D., Colmenares, L. U., Liu, J., Simmons, C. J., Britton, G., and Liu, R. S. H., “Fluorinated Analogs of the Carotenoprotein, a-Crustacyanin,”Bioorg. Chem., 26, 365-374 (1998).

Colmenares, Leticia U., and Lavina, Jessica, “Assesment of the Ambient Air Quality in Iligan City Using Standard and Phytomonitoring Methods,” Kimika, 14, 2, 75-82 (1998).

Liu, J., Colmenares, L. U., and Liu, R. S. H., "Fluorinated Astaxanthins" Tet. Lett., (1997).

Simmons, C. J., Colmenares, L. U. and Liu, R. S. H., "X-ray Crystal Structure of a Hindered 7-cis Isomer of Vitamin A. 7-cis-8-Fluororetinal," Tet. Lett., 37, 4103-04 (1996).

Colmenares, L. U., Mead, D., Yoshida, W., Alam, M. and Liu, R. S. H., "An FNMR Study of Bistrifluoromethylphenyl Bacteriorhodopsin Analogs", J. Phys. Chem., 100, 9172-74 (1996).

Colmenares, L. U., Niemczura, W. P., Asato, A. E. and Liu, R. S. H., "An FNMR Study of Rhodopsin Analogs: The Use of Vinyl Fluororetinal Chromophores", J. Phys. Chem., 100, 9175-80 (1996).

Colmenares, L. U. and Liu, R. S. H., "Fluorinated Phenylrhodopsin Analogs.Binding Selectivity, Restricted Rotation and 19F-NMR Studies," Tetrahedron, 52, 109-118 (1996).

Chen, R., Colmenares, L. U., Thiel, J. R. and Liu, R. S. H., "Spiral Hexatrienes. The Hindered cis Isomer of Mini-carotene-3 and Hexakis-(2,2',4,4',6,6'-trifluoromethyl)stilbene," Tet. Lett., 35, 7177-7180 (1994).

Liu, R. S. H., Krogh, E., Li Xiao-Yuan, Mead, D., Colmenares, L. U., Thiel, J. R., Ellis, J., Wong, D. and Asato, A. E., "Analyzing the red-shift characteristics of azulenic, naphthyl, other ring-fused and retinyl pigment analogs of bacteriorhodopsin," Photochem. Phobio., 58, 701-705 (1993).

Liu, R. S. H., Colmenares, L.U. and Niemczura, W. "19F-NMR Studies of Fluorinated Visual Pigment Analogs," in A. Shima, M. Ichahashi, Y. Fujiwara and H. Takebe (eds.) Frontiers of Photobiology, Elsevier Science Pub.,Amsterdam, 1993.

Colmenares, L.U. and Liu, R.S.H. "19F NMR Evidence for Restricted Rotation of the Retinyl Chromophore in Doubly Labeled Visual Pigment Analogs," J. Am. Chem. Soc., 114, 6933-34 (1992).

Liu, R.S.H. and Colmenares, L. "19F-NMR in Studies of Fluorinated Visual Pigment Analogs. A Method for Detecting Neighbouring Groups or Empty Space in a Binding Site," in J. L. Rigaud (ed.) Structures and Functions of Retinal Proteins, Colloque INSERM/John Libbey Eurotext Ltd., vol. 221, 251-254 (1992).

Mirzadegan, T., Humblet, C., Ripka, W. C., Colmenares, L.U. and Liu, R.S.H. "Modeling Rhodopsin, A Member of G-Protein Coupled Receptors, By Computer Graphics. Interpretation of Chemical Shifts of Fluorinated Rhodopsins," Photochem. Photobiol., 56, 883-893 (1992).

Colmenares, L.U. and Liu, R.S.H. "H-NMR and F-NMR Chemical Shifts of Fluorinated Retinals, Schiff Bases and Protonated Schiff Bases," Magnetic Resonance in Chemistry, 30, 490-496, (1992).

Colmenares, L.U. and Liu, R.S.H. "9,11-dicis-12-Fluororhodopsin. Chromophore Properties From 19F-NMR Studies," Photochem. Photobiol., 56, 101-105, (1992).

Colmenares, L.U. and Liu, R.S.H. "11-Methyl-demethylretinal and 11-methyl-9,13-didemethylretinal. Effect of Altered Methyl Substitution Pattern on Polyene Conformation Photoisomerization and Formation of Visual Pigment Analogs," Tetrahedron, 47, 3711-3718 (1991).

Colmenares, L. and Liu, R.S.H. "An Unexpected C-19 Product from Reaction of Retinal with MnO2. Structure Characterization and Bacteriorhodopsin Analogs," Tet. Lett., 32, 1933-1936 (1991).

Colmenares, L.U., Asato, A., Denny, M., Mead, D., Zingoni, J. and Liu, R.S.H. "NMR-Studies of Fluorinated Visual Pigment Analogs," Biophys. Biochem. Res. Comm., 178, 1337-1343, (1991).

Garcia, E.A. and Colmenares, L. "Synthesis of 2',3'-0-(ethoxy and dimethylamino) methylideneribonucleosides and other derivatives," Natural and Applied Science Bulletin, 34, 211-239 (1982).

Grants & Awards

Principal Investigator, Skin Pigmentation in Asians and Pacific Islanders, HS-BRIN/NIH, (5/02-12/04)
Principal Investigator, WCC Water Quality Assessment Project, Sea Grant/NOAA, (10/1/02-9/30/04).
Co-Investigator, SEP Supplementary Environmental Project Microscale Chemistry Lab Project, (9/1/02-12/03)
Principal Investigator, Chem 100 Laboratory Manual for Distance Education, Educational Improvement Fund, (12/1/00-8/01).
Principal Investigator, Water Quality Monitoring of He'eia Stream, Friends of He'eia State Park, (Jan-May, 2000).
Principal Investigator, Phytomonitoring of Air Pollutants in Iligan City, Philippine Council for Health Research & Development Research Grant, (1997-1998).


Treasurer, Hawaii Section- American Chemical Society, 2001 & 2002
Coordinator, National Chemistry Week, 2002
President, Filipino Association of University Women (FAUW), 2003
Recipient, UH Board of Regents Excellence in Teaching Award, 2003
WCC Wo Learning Champion, 2004

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Last Update: January 20, 2004