Methoxy-Substituted TQEN Family of Fluorescent Zinc Sensors
Yuji MikataMotoko WakamatsuAyano KawamuraNatsuko YamanakaShigenobu YanoAkira OdaniKazuko MorihiroSatoshi Tamotsu
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Abstract:
Two methoxy-substituted TQEN (N,N,N',N'-tetrakis(2-quinolylmethyl)ethylenediamine) derivatives, T(MQ)EN (N,N,N',N'-tetrakis(6-methoxy-2-quinolylmethyl)ethylenediamine) and T(TMQ)EN (N,N,N',N'-tetrakis(5,6,7-trimethoxy-2-quinolylmethyl)ethylenediamine), have been prepared, and their fluorescence properties with respect to Zn2+ coordination were investigated. Introduction of a methoxy substituent at 6-position of the quinoline ring enhances the fluorescence intensity by 10-fold, and the three methoxy substituents in the 5,6,7-positions afford significant enhancement of the long-wavelength component of the fluorescence of zinc complex. The substituents did not alter the binding affinity of these compounds toward zinc ion significantly. T(MQ)EN was proved to be effective in detection of zinc ion in cells by fluorescent microscopy.Keywords:
Ethylene diamine
Quinoline
In the title compound, C(28)H(20)Cl(2)N(2)O(2), the 2-chloro-quinoline and 6-chloro-quinoline ring systems are twisted slightly, making a dihedral angle of 4.05 (3)°. The dihedral angle between the 2-quinoline ring system and the phenyl ring attached to it is 74.43 (5)°. In the crystal structure, a pair of inter-molecular C-H⋯O hydrogen bonds connect the mol-ecules, forming centrosymmetric dimers with R(2) (2)(16) motifs. The dimers are further consolidated by a C-H⋯π inter-action and a π-π stacking inter-action with a centroid-centroid distance of 3.6562 (10) Å.
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Two ω-mercaptoalkoxy quinoline compounds:6-(ω-mercaptodecoxy)-quinoline and 2-(ω-mercaptodecoxy)-4-methyl-quinoline were succesfully synthesized by reacting quinoline with 1,10- dibromodecane and thiourea in alkaline solution. The intermediates and products were characterized by IR, 1H NMR and MS.
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Abstract The synthesis of the novel naphtho[2′,1′:4,5]thieno[2,3‐ c ]quinoline (11) ring system and four of the isomeric monomethyl derivatives is described.
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Abstract The synthesis of two previously unknown unsubstituted heterocyclic ring systems namely, benzo[ h ][1]benzothieno[2,3‐ c ]quinoline ( 6 ) and benzo[ f ][1]benzothieno[2,3‐ c ]quinoline ( 12 ) is reported. These two novel ring systems have been assembled by photocyclization of the appropriate amides.
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Photobases are compounds that become strong bases after electronic excitation. Recent experimental studies have highlighted the photobasicity of the 5-R quinoline compounds, demonstrating a strong substituent dependence to the pKa*. In this paper, we describe our systematic study of how the thermodynamic driving force for photobasicity is tuned through substituents in four families of nitrogen-containing heterocyclic aromatics. We show that substituent position and identity both significantly impact the pKa*. We demonstrate that the substituent effects are additive and identify many disubstituted compounds with substantially greater photobasicity than the most photobasic 5-R quinoline compound identified previously. We show that the addition of a second fused benzene ring to quinoline, along with two electron-donating substituents, lowers the S0 → SPBS vertical excitation energy into the visible region while still maintaining a pKa* > 14. Overall, the structure-function relationships developed in this study provide new insights to guide the development of new photocatalysts that employ photobasicity.
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In the title compound, C15H17N3O, the aldehyde group is twisted relative to the quinoline group by17.6 (2)° due to the presence of a bulky piperazinyl group in the ortho position. The piperazine N atom attached to the aromatic ring is sp (3)-hybridized and the dihedral angle between the mean planes through the the six piperazine ring atoms and through the quinoline ring system is 40.59 (7)°. Both piperazine substituents are in equatorial positions.
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In the title compound, C(23)H(15)Cl(2)NS, the quinoline system is almost planar [r.m.s. deviation = 0.013 (2) Å]. The phenyl group is disordered over two positions with site occupancies of 0.55 and 0.45, and is oriented in a nearly perpendicular configuration to the quinoline ring [the dihedral angles between the quinoline ring and the major and minor disordered components of the phenyl ring are 81.8 (2) and 71.6 (2)°, respectively]. The dihydro-thiene ring adopts an envelope conformation. The dihedral angle between the chloro-phenyl ring and the quinoline system is 79.32 (1)°. In the crystal weak C-H⋯π inter-actions occur.
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Photobases are compounds which become strong bases after electronic excitaton into a charge-transfer excited state. Recent experimental studies have highlighted the photobasicity of the 5-R quinoline compounds, demonstrating a strong substituent dependence to the pK a * . Here we describe our systematic study of how the photobasicity of four families of nitrogen-containing heterocyclic aromatics are tuned through substituents. We show that substituent position and identity both significantly impact the pK a * . We demonstrate that the substituent effects are additive and identify many disubstituted compounds with substantially greater photobasicity than the most photobasic 5-R quinoline compound identified previously. We show that the addition of a second fused benzene ring to quinoline, along with two electron-donating substituents, lowers the vertical excitation energy into the visible while still maintaining a pK a * > 14. Overall, the structure-function relationships developed in this study provide new insights to guide the development of new photocatalysts that employ photobasicity.
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Abstract The synthesis of two previously unknown heterocyclic ring systems, namely benzo[ h ]naphtho[2′,1′:4,5]thi‐eno[2,3‐ c ]quinoline (1) and benzo[ f ]naphtho[2′,1:4,5]thieno[2,3‐ c ]quinoline (2) was accomplished via photocyclization of the appropriate amides followed by chlorination and catalytic dechlorination. The total assignment of 1 H and 13 C nmr spectra of 2 was determined utilizing two‐dimensional nmr methods, providing unequivocal structural proof of the two novel polycyclic ring systems.
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Abstract The synthesis of two previously unknown heterocyclic ring systems, namely, thieno[3′,2′:4,5]thieno[2,3‐ c ]‐quinoline and thieno[2′,3′:4,5]thieno[2,3‐ c ]quinoline is reported. These two novel ring systems were assembled by photocyclization of the appropriate anilides.
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