*K. Rengan and R. Engel, "Phosphonium Cascade Molecules," Chem. Commun., 1084 (1990).
*K. Rengan and R. Engel, "The Synthesis of Phosphonium Cascade Molecules," J. Chem. Soc., Perkin Trans. I, 987 (1991).
*R. Engel, K. Rengan, and C. Milne, "Cationic Cascade Molecules," Polym. Prepr., 32, 601 (1991).
*R. Engel, "Cascade Molecules," Polymer News, 17, 301 (1992).
*K. Rengan and R. Engel, "Ammonium Cascade Molecules," J. Chem. Soc., Chem. Commun., 757 (1992).
*R. Engel, K. Rengan, and C.-s. Chan, "Phosphorus Cascade Molecules," Phosphorus and Sulfur, 77, 221 (1993).
*R. Engel, K. Rengan, and C.-s. Chan, "Cascade Molecules Centered About Phosphorus," Heteroatom Chem., 4, 181 (1993).
*R. Engel, "Ionic Dendrimers and Related Materials," Advances in Dendritic Macromolecules, 2, 73 (1995).
*A. Cherestes and R. Engel, "Dendrimeric Ion Exchange Materials," Polymer Commun., 35, 3343 (1994).
*J. Fabian, T. October, A. Cherestes and R. Engel, "Polycations: Syntheses of Polyammonium Strings as Antibacterial Agents," Synlett, 1007 (1997).
*A. Cherestes, T. October and R. Engel, "Polycations. II. Chiral Ammonium Dendrimer Synthesis," Heteroatom Chem., 9, 485 (1998).
*V. Shevchenko and R. Engel, "Polycations. III. Synthesis of Polyphosphonium Salts for Use as Antibacterial Agents," Heteroatom Chem., 9, 495 (1998).
*T.C. Strekas, R. Engel, K. Locknauth, J. Cohen and J. Fabian, "Polycations. 5. Inducement of Y-DNA Circular Dichroism Signals for Duplex Deoxyribonucleotide Homopolymers by Polycationic Strings," Arch. Biochem. Biophys., 364, 129 (1999).
*R. Engel, V. Shevchenko, S. Lall, B. Tropp, N. Lau and T. Strekas, "Synthesis and Biological Activities of Phosphorus-Containing Polycationic Strings," Phosphorus and Sulfur, 147, 83 (1999).
*J. I. Cohen, L. Traficante, P. W. Schwartz and R. Engel, "Polycations. 4. Synthesis and Antihydrophobic Effect of Polycationic Strings," Tetrahedron Lett., 39, 8617 (1998).
*J. I. Cohen, A. Rusinowski, T.C. Strekas and R. Engel, "Polycations. 6. Polycationic Heterocyclic Salts: Their Synthesis and Effect on Double Stranded DNA," Heteroatom Chem., 10, 559 (1999).
*J. I. Cohen and R. Engel, "Polycations. 7. Polycationic Cyclic Alkynes," Synth. Commun., 30, 2161 (2000).
*J. I. Cohen and R. Engel, "Polyammonium Organic Salts - Syntheses and Properties," Trends in Organic Chemistry, 7, 151 (1998).
*J. I. Cohen, S. Castro, J.-a. Han, V. Shteto and R. Engel, "Polycations. IX. Polyammonium Derivatives of Cyclodextrins-Syntheses and Binding to Organic Oxyanions," Heteroatom Chem., 11, 546 (2000).
*S. I. Lall, D. Mancheno, S. Castro, V. Behaj, J. I. Cohen and R. Engel, "Polycations. X. LIPs, a New Category of Ionic Liquid Based on Polyammonium Salts," J. Chem. Soc., Chem. Commun., 2413 (2000).
*R. Engel, J. I. Cohen and S. Lall, "A New Category of Liquid Salt - Liquid Ionic Phosphates (LIPs)," Phosphorus and Sulfur, 177, 1441 (2002).
*S. I. Lall, D. Mancheno, R. Casiano, S. Castro, A. Rikin, J. I. Cohen and R. Engel, "LIPs - Electrochemical and Spectroscopic Characteristics," Phosphorus and Sulfur, 177, 2267 (2002).
*J. I. Cohen, M. Thomas, A. Rikin, S. Castro, V. Behaj, C. Massone, J. Gaillard, S. Lall and R. Engel, "LIPs - Syntheses of Phosphonium and Ammonium Liquid Ionic Phosphates," Phosphorus and Sulfur, 177, 2265 (2002).
* V. Behaj, J.I. Cohen and R. Engel, "Polycations. XI. Polycationic Modified Paper for Chromatography," Analytical Letters, 35, 1715 (2002).
*S. Lall, V. Behaj, D. Mancheno, R. Casiano, M. Thomas, A. Rikin, J. Gaillard, R. Raju, A. Scumpia, S. Castro, R. Engel and J. I. Cohen, "Polycations. 12. The Synthesis of Liquid Ionic Phosphates (LIPs) from Mono- and Polycationic Ammonium Halides," Synthesis, 1530 (2002).
*T. Abel, J. I. Cohen, R. Engel, M. Filshtinskaya, A. Melkonian and K. Melkonian, "Preparation and Investigation of Antibacterial Carbohydrate-based Surfaces," Carbohydrate Research, 337, 2495 (2002).
*J. I. Cohen and R. Engel, "Organic Polycationic Salts - Syntheses and Applications," Current Organic Chemistry, 6, 1453 (2002).
* J.I. Cohen, V. Shteto and R. Engel, "Polycations. 8. The Synthesis of Polycationic Rings," Synthesis, 1263 (2000).
*T. Abel, J.I. Cohen, J. Escalera, R. Engel, M. Filshtinskaya, R. Fincher, A. Melkonian, and K. Melkonian, "Polycations. 14. Preparation and investigation of protein-based antibacterial surfaces," J. Textile and Apparel Tech. and Management, 3, 1 (2003).
*J.I. Cohen, T. Abel, D. Burkett, R. Engel, J. Escalera, M. Filshtinskaya, R. Hatchett, M. Leto, Y. Melgar, and K. Melkonian, "Polycations. 15. Polyammonium Surfaces - A New Approach to Antifungal Activity," Lett. Drug Design and Discovery, 1, 1 (2004).
*R. Engel, S. Lall-Ramnarine, D. Coleman and M. Thomas,, "New cations for ionic liquids, including chiral adjuncts with phosphate and sulfonylimide anions," Proceedings of the Ionic Liquids for Organic Synthesis Symposium, American Chemical Society Symposium Series #950, 259 (2007).
*R. Engel, J.I. Cohen and K. Melkonian, "Antimicrobial surfaces," Proceedings of the 2003 Joint Service Scientific Conference on Chemical & Biological Defense Research, #5, Individual Protection (2004).
*C. Massone and R. Engel, "Polycations. 16. Polyphosphonium species Containing Phosphorus-Phosphorus Bonds," Pol. J. Chem., 79, 481 (2005).
*E. Gordon, J-L. Cohen, R. Engel and G.W. Abbott, "1,4-Diazabicyclo[2.2.2]octane derivatives: a novel class of voltage-gated potassium channel blockers," Molecular Pharmacology, 69, 718 (2006).
*J. Wishart, S. Lall-Ramnarine, R. Raju, A. Scumpia, S. Bellevue, R. Ragbir, and R. Engel, "Spectra and solvation dynamics of the electron in ionic liquids," Radiat. Phys. Chem., 72, 99 (2005).
*R. Engel, J.I. Cohen, and K. Melkonian "Antimicrobial Surfaces," U.S. Patent 7,241,453, 10 July 2007.
*M. Thomas, L. Rothman, J. Hatcher, P. Agarkar, R. Ramkirath, S. Lall-Ramnarine, and R. Engel, "Synthesis and Thermochemical properties of Stereoisomeric Dihydroxy- and Tetrahydroxyalkylammonium Salts," Synthesis, 1437-1444 (2009).
*Y. He, J. Pohl, R. Engel, L. Rothman, and M. Thomas, "Preparation of ionic liquid based solid-phase microextraction fiber and its application to forensic determination of methamphetamine and amphetamine in human urine," J. Chromatography A, 1216, 4824-4830 (2009).