CT-Operated Bifunctional Fluorescent Probe Based on a Pretwisted Donor–Donor–Biphenyl

Abstract

Taking into account the structural requirements for TICT-type sensor molecules, a general synthetic route to derive pH and cation-responsive pretwisted donor (D)-donor (D) biphenyls (b) equipped with donor receptors is developed and a first model compound containing a mono aza-15-crown-5 and a DMA receptor is synthesized, see Scheme 1. The spectroscopic properties of this new bifunctional D-D biphenyl are studied in the non-polar and polar solvents cyclohexane, acetonitrile, and methanol. Protonation as well as complexation studies are performed with the representative metal ions Na(I), K(I), Ca(II), Ag(I), Zn(II), Cd(II), Hg(II), and Pb(II) to reveal the potential of this molecule for communication of whether none, only one, or both binding sites are engaged in analyte coordination by spectroscopically distinguishable outputs. The results are compared to those obtained with closely related donor (D)-acceptor (A) substituted biphenyl-type sensor molecules and are discussed within the framework of neutral and ionic D-A biphenyls.

Biphenyl-type sensing system in proton-rich environment by fluorescence and quantum-chemical calculations

“…An S-H bond is observed at Table 2 Optimized torsional angle of BP1 molecule: ground state (GS) and excited state (ES); effect of the environment. a -[C 2 -C 1 -C 7 2661 cm À 1 in the IR spectrum generated by the optimizing program, as shown in Fig. 9A and B.…”

“…This suggests that not only the polarity of the solvent but also solutesolvent specific interactions play an important role. The photophysics of biphenyl-based compounds is strongly affected by hydrogen bonding [7][8][9][10][11], but the effect is also dependent on particular derivatives. In contrast to the weak solvent dependence of the absorption spectrum, the fluorescence emission spectra are strongly solvent dependent, showing change in the character of the electronic state through the solvent relaxation in the excited state [12][13].…”

“…That shows the molecular geometry change in the excited state. Those biphenyles containing amino groups with free electrons at the nitrogen atom usually form hydrogen bonds in their ground state in protic solvents, which then are going to be broken under excitation [7]. Obviously, this process is dependent on reagents through kinetic rates, which become slow in alcohol and polar environment.…”

Multimodal Metal Cation Sensing with Bis(macrocyclic) Dye

“…For the dye 1, the fluorescence decay profiles could be fitted to at least three exponentials. Based on previous studies, we attribute the components in the decay kinetics as follows: the short component predominantly arises from the twist around the single bond in the CH-PhN unit analogous to its parent molecule M2, thereby implying a "loose bolt" relaxation pathway; [19] the second component arises due to "anti-syn" population equilibration of the benzo-15-crown-5 moiety in the exited state; and the longer component is due to isomerization of the M1 subunit. Such a presence of temporalspectral signatures related to different relaxation processes occurring at the same time in the solution of 1 suggests that two distinct ICTs, which do not interfere with each other and are located on different parts of the compound, can be excited despite the fact that the HOMO is involved only when ICT occurs between the 4-(dimethylamino) phenyl group and N-methylpyridinium and the lower-lying occupied orbital participates when ICT is observed between the benzo-15-crown-5 unit and N-methylpyridinium.…”

Verknüpfung von Mikrokristallen durch kooperative koordinative Wechselwirkungen

“…B. der Absorption und Emission); [21,22] 3) die Zn-Terpyridinkomplexe haben entweder eine 1:1- [18] oder eine 1:2-Stöchiometrie, [23] ausschließlich Aggregate aus abwechselnd rot und grün emittierenden Zeolithen entstehen sollten, zeigte eine Analyse eine 1:1-Verteilung von homo-(nur rot oder nur grün) und heterochromen Anordnungen, was darauf hinweist, dass Zink die Bitpy-Gruppen "durcheinanderwürfelt". Die REMAnalyse der Lösung ergab, dass eine große Zahl von Aggregaten entsteht (Hintergrundinformationen) und dass die Zeolithe auch tatsächlich über die Bitpy-funktionalisierten Stirnseiten verknüpft sind.…”