Ortho-phenylenediamine-based open and macrocyclic receptors in selective sensing of H2PO4(-), ATP and ADP under different conditions

Efficient fluorescent recognition of ATP/GTP by a water-soluble bisquinolinium pyridine-2,6-dicarboxamide compound. Crystal structures, spectroscopic studies and interaction mode with DNA

The new dicationic pyridine-2,6-dicarboxamide-based compound 1 bearing two N-alkylquinolinium units was synthesized, structurally determined by single-crystal X-ray diffraction, and studied in-depth as a fluorescent receptor for nucleotides and inorganic phosphorylated anions in pure water. The addition of nucleotides to 1 at pH = 7.0 quenches its blue emission with a selective affinity towards adenosine 5'-triphosphate (ATP) and guanosine 5'-tripohosphate (GTP) over other nucleotides such CTP, UTP, ADP, AMP, dicarboxylates and inorganic anions. On the basis of the spectroscopic tools (1H, 31P NMR, UV-vis, fluorescence), MS measurements and DFT calculations, receptor 1 binds ATP with high affinity (log K = 5.04) through the simultaneous formation of strong hydrogen bonds and π-π interactions between the adenosine fragment and quinolinium ring with binding energy calculated in 8.7 kcal mol-1. High affinity for ATP/GTP is attributed to the high acidity of amides and preorganized rigid structure of 1. Receptor 1 is an order of magnitude more selective for ATP than GTP. An efficient photoinduced electron transfer quenching mechanism with simultaneous receptor-ATP complexation in both the excited and ground states is proposed. Additionally, multiple spectroscopic studies and molecular dynamics simulations showed that 1 can intercalate into DNA base pairs.

Azulene-based fluorescent chemosensor for adenosine diphosphate

AzuFluor® 435-DPA-Zn, an azulene fluorophore bearing two zinc(II)-dipicolylamine receptor motifs, exhibits fluorescence enhancement in the presence of adenosine diphosphate. Selectivity for ADP over ATP, AMP and PPi results from appropriate positioning of the receptor motifs, since an isomeric sensor cannot discriminate between ADP and ATP.

An “off–on” fluorescent naphthalimide-based sensor for anions: its application in visual F− and AcO− discrimination in a self-assembled gel state

Herein, we report a novel fluorescent organogelator that could discriminate F⁻ from AcO⁻ in both solution and gel systems.

Molecular Receptors for Recognition and Sensing of Nucleotides

Nucleotides are constituents of nucleic acids and they have a variety of functions in cellular metabolism. Synthetic receptors and sensors are required to reveal the role of nucleotides in living organisms and mechanisms of signal transduction events. In recent years, a large number of nucleotide-selective synthetic receptors have been devised, which utilize different molecular designs and sensing mechanisms. This Minireview presents recent progress in the design of synthetic molecular receptors for selective recognition of nucleotides in aqueous solution. The binding properties of receptors and the origins of their selectivity for a particular nucleotide are discussed.

Effect of preorganization on the affinity of synthetic DNA binding motifs for nucleotide ligands

Triplexes with a gap in the purine strand have been shown to bind adenosine or guanosine derivatives through a combination of Watson-Crick and Hoogsteen base pairing. Rigidifying the binding site should be advantageous for affinity. Here we report that clamps delimiting the binding site have a modest effect on affinity, while bridging the gap of the purine strand can strongly increase affinity for ATP, cAMP, and FAD. The lowest dissociation constants were measured for two-strand triple helical motifs with a propylene bridge or an abasic nucleoside analog, with Kd values as low as 30 nM for cAMP in the latter case. Taken together, our data suggest that improving preorganization through covalent bridges increases the affinity for nucleotide ligands. But, a bulky bridge may also block one of two alternative binding modes for the adenine base. The results may help to design new receptors, switches, or storage motifs for purine-containing ligands.

Making pyrophosphate visible: the first precipitable and real-time fluorescent sensor for pyrophosphate in aqueous solution

An in situ generated Zn²⁺ complex of di-2-(picoly) amine BINOL–DPA was presented as a precipitable and real-time fluorescent sensor for PPi with a detection limit of 95 nm, and it could be successfully applied in imaging PPi in living cells.

Preassembly-driven ratiometric sensing of H2PO4− anions in organic and aqueous environments

The preassembly phenomenon of R1 facilitates novel ratiometric fluorescence sensing of H₂PO₄⁻ in organic and aqueous environments.

Pyridinum-based flexible tripodal cleft: a case of fluorescence sensing of ATP and dihydrogenphosphate under different conditions and cell imaging

Pyridinium-based chemosensor 1 built on tris(aminomethyl)amine (tren) has been designed, synthesized and established as a chemosensor for ATP over ADP, AMP and a series of other anions in aqueous CH₃CN at pH 6.5.

A benzimidazolium-based new flexible cleft built on the piperazine unit: a case of selective fluorometric sensing of ATP

A benzimidazole-based compound 1 which is highly selective and sensitive towards ATP over ADP and AMP in CH₃CN/H₂O (1 : 1, v/v, using 10 mM HEPES buffer, pH 6.4) has been designed and synthesized. Compound 1 can detect the presence of ATP in Human cervical cancer cells (HeLa).

Progress of 3-aminopyridinium-based synthetic receptors in anion recognition

This review describes the overall development on synthetic receptors built on the pyridinium motif with different functionalities at the 3-position in anion recognition.

Recent advances in H2PO4− fluorescent sensors

The recent advances in H₂PO₄⁻ fluorescent sensors were thoroughly reviewed.