1. International Scientific and Technological Cooperation Base of Water Retention Chemical Functional Materials College of Chemistry and Chemical Engineering Northwest Normal University Lanzhou Gansu 730070 People's Republic of China
2. College of Chemical Engineering and Technology Key Laboratory for New Molecule Design and Function of Gansu Universities Tianshui Normal University Tianshui 741001 People's Republic of China
3. Department of Chemistry University of Liverpool Crown Street Liverpool L69 7ZD UK