- A Molecular Imaging Approach to Mercury Sensing Based on Hyperpolarized 129Xe Molecular Clamp Probe
-
Mercury pollution, in the form of mercury ions (Hg2+), is a major health and environmental hazard. Commonly used sensors are invasive and limited to point measurements. Fluorescence-based sensors do not provide depth resolution needed to image spatial distributions. Herein we report a novel sensor capable of yielding spatial distributions by MRI using hyperpolarized 129Xe. A molecular clamp probe was developed consisting of dipyrrolylquinoxaline (DPQ) derivatives and twocryptophane-A cages. The DPQ derivatives act as cation receptors whereas cryptophane-A acts as a suitable host molecule for xenon. When the DPQ moiety interacts with mercury ions, the molecular clamp closes on the ion. Due to overlap of the electron clouds of the two cryptophane-A cages, the shielding effect on the encapsulated Xe becomes important. This leads to an upfield change of the chemical shift of the encapsulated Xe. This sensor exhibits good selectivity and sensitivity toward the mercury ion. This mercury-activated hyperpolarized 129Xe-based chemosensor is a new concept method for monitoring Hg2+ ion distributions by MRI. In a pinch: A novel sensor is reported that is capable of yielding spatial distributions of mercury ions by MRI, using hyperpolarized 129Xe. This clamp probe (see figure) consists of dipyrrolylquinoxaline (DPQ) derivatives and two cryptophane-A cages. The DPQ derivatives act as cation receptors, whereas cryptophane-A acts as a suitable host molecule for xenon. This sensor exhibits good selectivity and sensitivity toward the mercury ions.
- Guo, Qianni,Zeng, Qingbin,Jiang, Weiping,Zhang, Xiaoxiao,Luo, Qing,Zhang, Xu,Bouchard, Louis-S.,Liu, Maili,Zhou, Xin
-
supporting information
p. 3967 - 3970
(2016/03/16)
-
- Dipyrrolylquinoxaline difluoroborates with intense red solid-state fluorescence
-
A set of organic fluorescent dyes of dipyrrolylquinoxalines (PQs 4-6) and their BF2 complexes (BPQs 1-3) were synthesized from commercial reagents, and were characterized by their X-ray structural analysis, and optical and electrochemical properties. BPQs 1-3 showed intense broad absorption in the visible region in the solution-state. In comparison with that of PQs 4-6, there is an over 110 nm red-shift of the absorption maximum in the BPQs 1-3 (up to 583 nm). Interestingly, dyes 1-6 all exhibit red solid-state fluorescence with moderate to high fluorescence quantum yields except for PQ 4 which showed bright yellow solid-state fluorescence. X-ray structures of BPQs 2-3 showed the planar structure of quinoxaline with one pyrrole unit via the BF2 chelation and the almost perpendicular orientation of the uncoordinated pyrrole to the NBN core plane (the dihedral angle of 70-73°). The extended π-conjugation was in good agreement with the observed red-shift of the spectra. These dyes formed well-ordered intermolecular packing structures via the intermolecular hydrogen bonding between the N atoms of quinoxaline moieties and the NH units of adjacent pyrroles. The lack of π-π stacking in their crystal packing structures may explain the interestingly intense solid-state fluorescence of these dyes.
- Yu, Changjiang,Hao, Erhong,Li, Tingting,Wang, Jun,Sheng, Wanle,Wei, Yun,Mu, Xiaolong,Jiao, Lijuan
-
supporting information
p. 13897 - 13905
(2015/08/18)
-
- Fluoride-selective optical sensor based on the dipyrrolyl- tetrathiafulvalene chromophore
-
A chemosensor bearing dipyrrolyl motifs as recognition sites and a tetrathiafulvalene redox tag has been evaluated as an optical and redox sensor for a series of anions (F-, Cl-, Br-, HSO 4-, CH3COO-, and H 2PO4-) in DCM solution. The receptor shows specific optical signaling for fluoride but little electrochemical effect in solution. The solid-state performance of the sensor leads to measurable changes in water. Design implications towards better systems based on these results and other examples are discussed.
- Rivadehi, Shadi,Reid, Ellen F.,Hogan, Conor F.,Bhosale, Sheshanath V.,Langford, Steven J.
-
supporting information; experimental part
p. 705 - 709
(2012/02/03)
-
- Dipyrrolylquinoxaline-bridged hydrazones: A new class of chemosensors for copper(II)
-
Novel 2,3-bis(1H-pyrrol-2-yl)quinoxaline-fun-ctionalized hydrazones were prepared and characterized as new chemosensors for copper(II) ion. The binding properties of the compounds 4,5, 6 and 7 for cations were examined by UV-vis, fluorescence spectroscopy, and linear sweep vol-tammetric experiments (LSV). The results indicate that a 1:1 stoichiometric complex is formed between compound 4 (or 5, 6, 7) and copper(II) ion, and the association constant is 1.3 × 105 M-1 for 4, 2.1 × 106M-1 for 5, 4.1 × 105M-1 for 6 and 8.0 × 10 M -1 for 7, respectively. The recognition mechanism between compound 4 (or 5, 6, 7) and metal ion was discussed based on their electrochemical properties, absorbance changes, and the fluorescence quenching effect when they interact with each other. Control experiments revealed that compound 4 (or 5, 6, 7) has a highly selective response to copper (II) ion.
- Guo, Qian-Ni,Zhong, Cheng,Lu, Yun-Guo,Shi, Chuang,Li, Zao-Ying
-
scheme or table
p. 79 - 88
(2012/08/28)
-
- A novel class of Cd(ii), Hg(ii) turn-on and Cu(ii), Zn(ii) turn-off Schiff base fluorescent probes
-
N,N′-((5,5′-(Quinoxaline-2,3-diyl)bis(1H-pyrrole-5,2-diyl)) bis(methanylylidene))bis(4-methoxyaniline) 4 and N,N′-((5,5′- (quinoxaline-2,3-diyl)-bis(1H-pyrrole-5,2-diyl))bis(methanylylidene))dianiline 5 have been prepared and structurally characterized. The X-ray crystal structures of compounds 4 and 4a have been determined. These compounds displayed good sensitivity toward transition metal ions with Cd(ii), Zn(ii) turn-on and Cu(ii), Hg(ii) turn-off in fluorescence. It is an elegant example of on/off behavior like a lamp. When Cd(ii) or Zn(ii) is added into compounds 4 or 5, the lamp will switch on, and then when Cu(ii) or Hg(ii) is added into the mixture, the lamp will switch off. The binding properties of 4 and 5 for cations were examined by fluorescence spectroscopy. The fluorescence data and crystal structure indicate that a 1:1 stoichiometry complex is formed between compound 4 (or 5) and metal ions, and the binding affinity is very high. The recognition mechanism between compound 4 (or 5) and metal ion was discussed based on the their chemical constructions and the CHEF/CHEQ effect when they interacted with each other.
- Hu, Yuan,Li, Qian-Qian,Li, Hua,Guo, Qian-Ni,Lu, Yun-Guo,Li, Zao-Ying
-
scheme or table
p. 11344 - 11352
(2011/02/16)
-
- Phenanthroline complexes bearing fused dipyrrolylquinoxaline anion recognition sites: Efficient fluoride anion receptors
-
Novel anion recognition host molecules, tris-1,10-phenanthroline cobalt(III) and bis-2,2-bipyridine mono-1,10-phenanthroline ruthenium(II) complexes bearing fused dipyrrolylquinoxaline moieties have been synthesized. As determined by UV-vis spectroscopic and electrochemical studies, these metal complexes bind fluoride with high affinity in polar media both in absolute terms and relative to the metal-free phenanthroline dipyrrolylquinozaline precursor from which they are derived (fluoride is bound to the tris-1,10-phenanthroline cobalt(III) dipyrrolylquinoxaline system with a 1:1 binding constant of 54000 M-1 in DMSO). The large observed binding constants are ascribed to two factors, (i) the presence of a phenanthroline-coordinated cationic charge that decreases the electron density on the pyrrole NH protons and (ii) pure electrostatic effects. Copyright
- Mizuno, Toshihisa,Wei, Wen-Hao,Eller, Leah Renee,Sessler, Jonathan L.
-
p. 1134 - 1135
(2007/10/03)
-
- THERMOLYTIC REMOVAL OF t-BUTYLOXYCARBONYL (BOC) PROTECTING GROUP ON INDOLES AND PYRROLES
-
The t-Butyloxycarbonyl (BOC) group on indoles and pyrroles can be removed cleanly and in high yield by simple thermolysis: no acid, no base, no solvent is required.
- Rawal, Viresh H.,Cava, Michael P.
-
p. 6141 - 6142
(2007/10/02)
-