Turn-on Phosphorescence by Metal Coordination to a Multivalent Terpyridine Ligand: A New Paradigm for Luminescent Sensors

Abstract

A hexathiobenzene molecule carrying six terpyridine (tpy) units at the periphery has been designed to couple the aggregation induced phosphorescence, displayed by the core in the solid state, to the metal binding properties of the tpy units. Upon Mg(2+) complexation in THF solution, phosphorescence of the hexathiobenzene core is turned on. Metal ion coordination yields the formation of a supramolecular polymer which hinders intramolecular rotations and motions of the core chromophore, thus favoring radiative deactivation of the luminescent excited state. Upon excitation of the [Mg(tpy)2](2+) units of the polymeric structure, sensitization of the core phosphorescence takes place with >90% efficiency. The light-harvesting polymeric antenna can be disassembled upon fluoride ion addition, thereby switching off luminescence and offering a new tool for fluoride ion sensing. This unique system can, thus, serve as cation or anion sensor.

Synthesis and chemosensory properties of terpyridine-containing diblock polycarbazole through RAFT polymerization

“…Additionally, the dihedral angle (0.16°) between two neighboring pyridine rings with binding Zn 2+ was smaller than that without Zn 2+ (38.7°). These results indicate that the more highly planar and rigid terpyridineZn 2+ complex reduced the twist and vibration of the C-C polymer backbone and enhanced the charge transfer from donors to acceptors [41][42][43].…”

Principles of chemosensory system organization for detecting metal ions in aqueous solutions

“…Существующая в настоящее время флуоресцентная методика определения концентрации химических веществ в водном растворе основана на измерении изменения интенсивности или спектра люминесценции чувствительного по-крытия в присутствии определяемого вещества (аналита) [11][12][13][14]. Так, в случае люмокупферона в присутствии ионов меди происходит образование хорошо люминесцирующего фотодимера из слабо люминесцирующей формы реактива.…”

“…Некоторыми авторами отмечается ухудшение характеристик оптических сенсоров при длительном воздействии лазерного излучения [12], возникаю-щее вследствие деградации индикатора. Нами предложено использование коротких лазерных импульсов, с одной стороны, уменьшающих тепловое воздействие на люминофор и, как следствие, предотвращающих его деграда-цию, а с другой -позволяющих определить время жизни люминесценции чувствительного покрытия.…”

Cyclometalated Platinum(II) Terpyridylacetylide with a Bis(arylamine) Donor as a Proton-Triggered Luminescence Chemosensor for Zn2+

“…As expected, other common transition metal ions, such as Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , and Cu 2+ , exhibit dramatic luminescence quenching responses, because these metal ions possess low-energy excited states and can be involved in the photoinduced energy/electron transfer processes between the phosphorescent Pt(II) complex units and the metal-TPY complex core. 27 Surprisingly, alkali (Na + and K + ) and alkali-earth (Mg 2+ and Ca 2+ ) ions also cause its phosphorescence quenching. But the luminescence enhancement effect is observed in the presence of Zn 2+ or Cd 2+ ion with the filled d 10 electronic configuration.…”