1. NUS Graduate School - Integrative Sciences & Engineering Programme (ISEP), National University of Singapore, Singapore 117543, Singapore
2. Institute of Materials Research and Engineering (IMRE) Agency for Science, Technology and Research (A*STAR) 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Singapore
3. Department of Chemistry National University of Singapore 3 Science Drive 3 Singapore 117543, Singapore