Tetracyclines (TCs), broad spectrum antibiotics widely used in the prevention and treatment of infectious diseases, are amphoteric molecules containing several ionizable functional groups that exist predominantly as zwitterions at a given pH value. TCs are reported to undergo a wide variety of reactions at different pH values i.e. TCs form to anhydrotetracyclines at low pH, 4-epitetracyclines at pH 3-5 and isotetracyclines at high pH values. The pH-dependent absorbance and emission properties of tetracycline and its 10 analogs (4-epitetracycline, doxycyline, oxytetracycline, chlortetracycline, 4-epichlortetracycline, isochlortetracycline, methacycline, rolitetracycline, minocycline, and demeclocycline) were investigated and reported in this paper. The main focus of the study was on the pH dependent transformation of epichlortetracycline, chlortetracycline and isotetracycline at basic pH. Absorption, emission and time resolved spectroscopy were used to determine the behavior of the three TC derivatives at this condition. Increasing the buffer's ionic concentration leads to faster transformation to iCTC. A pH dependent transformation of CTC to iCTC was observed and the lifetimes of CTC and iCTC were determined to be 3.0 and 5.89 ns respectively. The distribution factor of CTC to iCTC at basic pH was also reported for the first time.

The environment is affected by the actions of mankind in multitudinous ways, many of which are detrimental, giving rise to pollution and toxic waste, ultimately making our planet less inhabitable. While remediation and new regulations help to prevent pollution and toxic waste, there is also a need to change the behavior of future generations of consumers and producers of new products. Future chemists and innovators are charged with the responsibility of developing new chemical processes and products that not only meet the needs of our growing population (in terms of energy, clean water and food), but also protect human health and the environment. Green Chemistry is a revolution in the design of molecules that provides new opportunities for economic development while considering the impact on health and the environment. Green Chemistry utilizes a set of guiding principles, originally provided by Anastas and Warner (Green Chemistry: Theory and Practice, 1998), aimed at decreasing/removing the use/generation of hazardous substances in the design, manufacture and application of products. To help improve the creative and innovative thinking behind Green Chemistry, it is important to expose chemistry students to these principles at the undergraduate level. While suitable Green Chemistry experiments are known, successful implementation requires running test trials and performing additional basic research. We have embarked upon the testing and further design of experiments for implementation into an undergraduate laboratory course and report our results in this endeavor.