Dendrimer chemistry is rapidly expanding for fundamental reasons as well as due to requirements in technological applications.1 A recent interesting development in dendrimer chemistry concerns the coordination of metal ions by interior branches or exterior units.
2-6Dendrimers containing photoactive units 7-17 are particularly interesting for two reasons: (1) cooperation among the photoactive components can allow the dendrimer to perform specific functions, and (2) changes in the properties of photoactive components can be exploited to monitor the participation of dendrimers in chemical processes.Polyphenols such as pyrogallol and gallic acid (GA) produce a singlet oxygen in the presence of hydrogen peroxide in an alkaline medium and emit light. GA has also been utilized for selective Co 2+ detection using a chemiluminescence (CL) flow injection system. The CL intensities of polyphenols are considerably weaker than those of luminal and acridinium ester, which are representative CL compounds. Hence, trans-4-(3-propionic acid) phenylboronic acid and 4-biphenylboronic acid in the presence of peroxidase or 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide have been used as an enhancer for highly sensitive polyphenol CL determination. However, methods to derive polyphenols with strong CL intensity have not been reported yet.
18In recent times, after a new polymer, poly(amidoamine) dendrimer, was synthesized, dendrimers have been applied to material engineering based on optics in nanoscale science. The poly(propylene amine) family that was functionalized in the periphery with fluorescent dansyl units interacts with Co
2+. More recently, acridinium dendrimers have been conjugated with bovine serum albumin, and its CL was estimated to be six times that of the acridinium salt.In this paper, we report the design of new types of polyphenol dendrimers having an increased number of chemiluminophores for high CL intensity; they also have hydroxyl groups in their periphery to form hydrogen bonds with an analyte. Polyphenol dendrimers having GA in the periphery were synthesized, and their CL was measured. We synthesized first-generation polyphenol dendrimers with GA units in the periphery by employing a divergent method using phenol, pyrocatechol, resorcinol, hydroquinone, 1,2,4-trihydroxybenzene, 3,4,5-trihydroxybenzene aniline, 1,2-diaminobenzene, and 1,3-diaminobenzene as the core molecules (Supporting information, Schemes 1 and 2).Experimental methods and physical data from polyol 1a-f to first-generation esters 5a-f have been reported in our previous paper.
19The mass spectra of the zero-generation esters 3a-f and first-generation esters 5a-5f were obtained by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI TOF MS) using 2,5-dihydroxybenzoic acid as the matrix. The amide group has a rigid, planer structure as a consequence of resonance interactions that give the amide bond ~40% double bond character. The planer conformation maximizes π-bonding overlap, which accounts for the amide group's ri...
