Chemosensors

Fleterocycles as chemosensors in molecular wire approach to sensory signal amplification 98ACR201. 

Jacques V, Desreux JF (2002) New Classes of MRI Contrast Agents. 221 123-164 James TD, Shinkai S (2002) Artificial Receptors as Chemosensors for Carbohydrates. 218 159-200... 

James TD, Shinkai S (2002) Artificial Receptors as Chemosensors for Carbohydrates. 218 ... 

Later in intra-uterine life, the human infant is susceptible to early chemical prompting, but again the affector route is not known with certainty. Neonatal discrimination in favour of familiar (maternal) amniotic fluid is demonstrable, suggesting that the foetus already has active chemosensory capacities (Schaal, 1998). Smell and taste are operative in the near full-term foetus since it shows detection of about 120 mg/day maternal intake of anethole (as anise condiments) within a few days before parturition this exposure induced subsequent preferential responses by babies to anethole (Schaal et ai, 2000). The human neonate is not likely to have its organ as a fully functioning chemosensor,... 

In support of this contention, the carrier protein Aphrodisin makes an early appearance in vaginal secretions. In pre-pubertal hamsters, it thus indicates chemosensory preparation for the onset of female maturity (Magert, 1999). The proven ability of the AOS to modulate the CNS-pituitary-gonadal axis by advancing or retarding endocrine activity (Chap. 5), underlines its role as primarily the chemosensor of the reproductive system. The adaptive consequence of responses, which allows an avoidance of premature breeding, or of a postponement of puberty, would seem to be advantageous. 

A Third Family of Metabotropic Glutamate Receptors and Chemosensors.93... 

FIGURE 2.3 The three main families of mammalian G-protein-coupled 7TM receptors in mammals. No obvious sequence identity is found between the rhodopsin-like family A, the glucagon/VIP/calcitonin family B, and the metabotropic glutamate/chemosensor family C of G-protein-coupled 7TM receptors, with the exception of the disulfide bridge between the top of TM-III and the middle of extracellular loop-2 (see Figure 2.2). Similarly, no apparent sequence identity exists among members of these three families and, for example the 7TM bitter taste receptors, the V1R pheromone receptors, and the 7TM frizzled proteins, which all are either known or believed to be G-protein-coupled receptors. Bacteriorhodopsins, which are not G-protein-coupled proteins but proton pumps, are totally different in respect to amino-acid sequence but have a seven-helical bundle arranged rather similarly to that for the G-protein-coupled receptors. 

A THIRD FAMILY OF METABOTROPIC GLUTAMATE RECEPTORS AND CHEMOSENSORS... 

McFarland SA, Finney NS (2001) Fluorescent chemosensors based on conformational restriction of a biaryl fluorophore. J Am Chem Soc 123 1260-1261... 

Bahr N, Tierney E, Reymond JL (1997) Highly Photoresistant chemosensors using acridone as fluorescent label. Tetrahedron Lett 38 1489-1492... 

Chang KC, Su I, Senthilvelan A, Chung W (2007) Triazole-modified calix[4]crown as a novel fluorescent on—off switchable chemosensor. Org Lett 9 3363-3366... 

An r/rr/mnv -squaraine-based chemosensor 23a absorbing at 635 nm (eM = 260,000 M 1cm 1) and emitting at 665 nm signals alkaline and earth-alkaline metal ions in millimolar concentrations in acetonitrile [81]. In presence of Na+ ions, the fluorescence signal weakly increases while it significantly decreases in presence of Ca2+, Mg2+, and Ba2+ and does not change substantially upon addition of K+ ions. The same squaraine 23a and the azacrown-squaraine 23b [82] were used for Na+ and K+ sensing in a plasticized PVC matrix [83]. The squaraine derivatives exhibited fluorescence emission based optical responses to... 

A Ca2+-specific fluorescent chemosensor 25 in aqueous buffer signals Ca2+ via a decrease in fluorescence intensity, whereas excess of Mg2+ ions has no effect on the emission [85]. This probe has limited solubility in aqueous solution after binding to Ca2+. A Zn2+ sensitive probe 26 showing different fluorescence responses depending on the complexation stoichiometry is described in [86],... 

The dihydroxyaniline-squaraine chromophore was used by Akkaya and Isgor in the fluorescent chemosensor 30 for the measurement of pH [90]. This chemosensor, having the molar absorptivity about 200,000 M em 1 and quantum yield 0.2,... 

Oguz U, Akkaya EU (1997) One-pot synthesis of a red-fluorescent chemosensor from an azacrown, phloroglucinol and squaric acid a simple in-solution construction of a functional molecular device. Tetrahedron Lett 38 4509 1512... 

Oguz U, Akkaya EU (1998) A squaraine-based sodium selective fluorescent chemosensor. Tetrahedron Lett 39 5857-5860... 

Akkaya EU, Turkyilmaz S (1997) A squaraine-based near IR fluorescent chemosensor for calcium. Tetrahedron Lett 38 4513—4516... 

Isgor YG, Akkaya EU (1997) Chemosensing in deep red a squaraine-based fluorescent chemosensor for pH. Tetrahedron Lett 38 7417-7420... 

Wang S, Chang YT (2006) Combinatorial synthesis of benzimidazolium dyes and its diversity directed application toward GTP-selective fluorescent chemosensors. J Am Chem Soc 128 10380-10381... 

Coskun A, Yilmaz MD, Akkaya EU (2007) Bis(2-pyridyl)-substituted boratriazaindacene as an NIR-emitting chemosensor for Hg(II). Org Lett 9 607-609... 

Killoran J, McDonnell SO, Gallagher JF et al (2008) A substituted BF2-chelated tetraaryla-zadipyrromethene as an intrinsic dual chemosensor in the 650-850 nm spectral range. New J Chem 32 483 189... 

Keywords Biofluids Chemosensors Emission spectroscopy Mechanosensors Optical properties Polarity Rheology Twisted intramolecular charge transfer Viscosity... 

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