August 5, 2010
School of Arts & Sciences, Amritapuri
As part of the India 4 EU program Dr. Zeena S. Pillai, Chairperson, Department of Chemistry, Amritapuri Campus, had the opportunity to work at the University of Bologna in Italy for two months recently.
Considered as one of the world’s top research groups in the field of Supramolecular Chemistry, the group includes, among other eminent scientists, Profs. Vincenzo Balzani, Paola Ceroni and Margherita Venturi.
What happens when one comes face-to-face with the author of textbooks one had used during one’s graduate studies? That was the question Dr. Zeena had in mind before meeting Prof. Balzani, who heads the research group.
“I was so surprised to realize that he was such a nice, simple and down-to-earth person.”
“While doing my Ph.D, I had read about University of Bologna, founded in 1088, the oldest continually-operating university in the world. Now years later I was working there!”
“I have gone abroad to several places for research purposes, but this was a very special experience for me that I will cherish forever”.
Dr. Zeena worked with Prof. Paola Ceroni on dendrimers that constitute a class of multibranched molecules that can exhibit a high degree of order due to their three dimensional architecture.
“They consist of a core upon which radially branched layers, termed generations, are attached,” she shared. See Complete Project Abstract »
Dr. Zeena was impressed to see the amount of attention being given to each and every minute detail and aspect of every research project. “The students also express their ideas and questions without inhibitions. At Amrita too, we try to make our classes more interactive and encourage students to express themselves freely.” she stated.
Dr. Zeena found people there extremely helpful and friendly. “They have expressed their wish to collaborate with us on various projects,” she shared.
“On June 23, before her return, Dr. Zeena delivered a talk about Chancellor Amma and Amrita Vishwa Vidyapetham at the University of Bologna. “They were enthusiastic upon hearing about our young institution and expressed their interest to visit the Amritapuri campus soon.”
“It was a wonderful experience for me overall. I interacted with many pioneers in the field. I would say that India 4 EU and the Erasmus Mundus programs help encourage researchers such as myself. Many thanks to the coordinators, Dr. Krishnashree, Mr. Pradeep Kumar and Ms. Livia who were there to help me tackle all administrative details related to the program.”
Studies on the Photophysical and Co-ordination Properties of Cyclam Core Dendrimers
Dendrimers constitute a class of multibranched molecules that can exhibit a high degree of order due to its three dimensional architecture. They consist of a core upon which radially branched layers, termed generations, are attached. One important characteristic of dendrimers is the presence of internal cavities where ions or neutral molecules can be encapsulated. Dendrimers that contain both luminescent units and coordination sites are interesting since they are capable of functioning as luminescent ligands for metal ions. In most cases, metal ion coordination by a dendrimer takes place by units like amines, amide or imine groups that are present along the dendrimer branches or attached to the periphery of the dendrimer. 
Coupling luminescence with metal coordination can be exploited for a variety of applications such as light harvesting, ion sensing, signal amplification etc. Metal ions in lanthanide family constitute an interesting class of luminescent metal ions due to their long lived and line-like emission bands which cover a spectral range from near –UV to the visible and NIR region. The luminescent lanthanide ions are usually coordinated to the ligands containing organic chromophores whose excitation followed by energy transfer causes the sensitized luminescence of the metal ion (antenna effect). It is to be noted here that the direct excitation of lanthanide ions is difficult due to the forbidden nature of their electronic transitions. Most of the investigations in the field of luminescent lanthanide complexes have been devoted to Eu3+ & Tb 3+ compopunds which emit in the visible spectral region and hence, are used as sensors, luminescent labels in fluoroimmune assays and time resolved microscopy. In most of the dendrimers reported in literature, metal ion coordination occurs through units such as amides, amines, imines, etc. present along the dendrimer branches or at the periphery. Except for the porphyrin-based dendrimers, only very few examples of dendrimers with a well defined metal coordinating core have been reported. The macrocylic ligand…1,4,8,11-tetraaza cyclotetradecane (cyclam), is one of the most extensively investigated macrocylic ligands in coordination chemistry.
Both cyclam and its derivatives in aqueous solution can be protonated and can coordinate metal ions such as Co (II), Ni(II), Cu(II) with high stability constants. They have been also studied as carriers of metal ions in antitumor and imaging applications and as anti-HIV agents. We selected dansylated dendrimers with cyclam core and studied its complexation properties with lanthanides.
