Available online at www.sciencedirect.com Spectrochimica Acta Part A 70 (2008) 532–536 Spectral investigation of coordination of cuprum cations and protons at PAMAM dendrimer peripherally modified with 1,8-naphthalimide units Ivo Grabchev a,∗ , Desislava Staneva b , Vladimir Bojinov b , Rosica Betcheva b , Vasilis Gregoriou c a Institute of Polymers, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria b University of Chemical Technology and Metallurgy, 1756 Sofia, Bulgaria c Institute of Chemical Engineering and High Temperature Chemical Processes, GR 26500 Patras, Greece Received 11 June 2007; received in revised form 18 July 2007; accepted 27 July 2007 Abstract The investigations aim at revealing the ability of a 1,8-napthalimide-modified poly(amidoamine) dendrimer from second generation to respond to the presence of cuprum cations and protons in the environment. It has been established that a single Cu 2+ cation present in the dendrimer molecule is capable of quenching more than 78% of its fluorescence what is an indication of high sensitiveness. An enhancement of the fluorescence emission of the dendrimer has been observed in acidic medium. It has been established that the processes of coordinating the ions in different sites of the dendrimer are reversible. © 2007 Elsevier B.V. All rights reserved. Keywords: PAMAM dendrimer; 1,8-Naphthalimide; Sensor; Fluorescence; Environment 1. Introduction Dendrimers have well defined three-dimensional macro- molecular structure. Investigations on the functional properties of these materials have been widely carried out [1–5]. Among the vanguard topics has been the design of luminescent dendrimers with regard to their exploitation, especially for detection of envi- ronment pollutants. In the respect great attention is being paid to altering the desired properties of the new materials. A route to tailor the behaviour of newly prepared dendrimers is intro- ducing fluorophres of various nature and fluorescence emission into their core or periphery. First Tomalia et al. [6] have reported on the synthesis of polyamidoamine (PAMAM) dendrimers. The specifics of these polymers are their interior containing both amide and ter- tiary amine groups, while their peripheries are functionalized with various functional groups able to furnish desired proper- ties. Recent investigations have demonstrated the potential of PAMAM dendrimer molecules to coordinate metal cations [7]. ∗ Corresponding author. Tel.: +359 2 9792293. E-mail address: grabchev@polymer.bas.bg (I. Grabchev). Our investigations on the synthesis and photophysical proper- ties of some PAMAM derivatives comprising 1,8-naphthalimide units in their periphery have been published [8]. Their fluo- rescence properties in the presence of different metal cations have showed that the dendrimers could acts as effective pho- toinduced electron transfer (PET) [9] fluorosensors for different metal cations. Herein we describe the functional properties of a second generation PAMAM dendrimer comprising 4- N,N-dimethylaminoethylamino-1,8-naphthalimide units in its periphery. Its capacities as highly sensitive PET sensor for cuprum cations and protons have been outlined. The emphasis in the investigations has been put on the complex influence of both analytes as well as the one of order of their addition to the dendrimer solution. 2. Experimental part 2.1. Materials and methods The modified PAMAM dendrimers with 1,8-napthalimide derivative under study have the structures presented in Scheme 1 [8f]. 1386-1425/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.saa.2007.07.057