Spiro Alexandratos

Dr. Spiro Alexandratos got his PhD from the University of California at Berkley. At Hunter College he teaches courses in polymer chemistry and environmental science and technology and conducts research centered around polymers.

• University of California at Berkley (PhD)

Courses taught have included:

• CHEM 36900 H Polymer Chemistry
• MHC 20000 Environmental Science and Technology

Research Focus

• Polymer chemistry
• Environmental chemistry

Research Statement

The Alexandratos Lab approaches radiochemistry from the standpoint of separations and of sensors.

*Ionic Crystals: Synthesis of modified structures and their study for environmental remediation* Ionic crystals are a class of inorganic polymers. With them, we are developing a new class of biocompatible inorganic /organic hybrid structures via green chemistry utilizing interfacial reactions. The building blocks for these coordination polymers are an ionic crystal, a modifier with an organic anion having a high affinity for the crystal’s cation, and substituents on the modifier which can change the hybrid’s polarity.

Generally, the ionic crystal M+X- is reacted with a modifier A+B- and, in an ion exchange reaction, M+ binds B- to yield a net solid-to-solid conversion. Examples of each component are hydroxyapatite (HAP, Ca10(PO4)6(OH)2), hydroxyethane-1,1-diphosphonate (HEDP), and alendronate (XDP). The polarity of the crystal can be varied further by incorporating transition and lanthanide metal ions.

The hybrids are subjected to characterization by a number of techniques, including FTIR, solid state NMR, electron microscopy, and X-ray diffraction. This research impacts environmental remediation, drug delivery, and valorization. First results with adsorption isotherms on a hybrid show it to have a high affinity for a dye, making it competitive with organic polymers: Modification of HAP with HEDP in the equation shown increases its affinity for methylene blue, a toxic dye contaminant in water from 10 mg MB /g HAP to 893 mg MB / g.

Since dyes are pollutants in rivers and other water supplies, the high capacity allows application to environmental remediation. That it is biocompatible gives it an important advantage over organic polymers. Biocompatibility combined with high capacity makes the modified HAP attractive for drug delivery applications.

Results with the dye imply high loading is possible with antibiotics. The modified HAP can be implanted and slowly release the antibiotic into the body. In terms of valorization, natural HAP derives from animal bones and other sources regarded as waste; We render this waste useful (i.e., valorize) by using it as a reactant in the modification reaction.

• Alexandratos, S.D.; Barak, N.; Bauer, D.; Davidson, F.T.; Gibney, B.R.; Hubbard, S.S.; Taft, H.; Westerhof, P. Sustaining Water Resources: Environmental and Economic Impact, ACS Sustainable Chemistry and Engineering, 2019, 7, 2879-2888
• Alexandratos, S.D.; Zhu, X. ATR-FTIR spectroscopy as a probe for metal ion binding onto immobilized ligands, Materials Chemistry and Physics, 2018, 218, 196-203
• Alexandratos, S.D.; Zhu, X. Through-bond communication between polymer-bound phosphinic acid ligands and trivalent metal ions probed with FTIR Spectroscopy, Vibrational Spectroscopy, 2018, 95, 80-89
• Alexandratos, S.D. From Ion Exchange Resins to Polymer-Supported Reagents: An Evolution of Critical Variables, Journal of Chemical Technology and Biotechnology 2018, 93, 20-27
• Alexandratos, S.D.; Zhu, X. The effect of hydrogen bonding in enhancing the ionic affinities of immobilized monoprotic phosphate ligands, Materials 2017, 10, 968-976
• Alexandratos, S.D.; Zhu, X.; Florent, M.; Sellin, R. Polymer-supported bifunctional amidoximes for the sorption of uranium from seawater, Industrial & Engineering Chemistry Research, 2016, 55, 4208 - 4216
• Zhu, X.; Alexandratos, S.D. Polymer-supported aminomethylphosphinate as a ligand with a high affinity for U(VI) from phosphoric acid solutions: combining variables to optimize ligand-ion communication, Solvent Extraction and Ion Exchange, 2016, 34, 290-295