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Full-Text Articles in Other Chemistry
The Role Of Anharmonicity In Hydrogen-Bonded Systems: The Case Of Water Clusters, Berhane Temelso, George Shields
The Role Of Anharmonicity In Hydrogen-Bonded Systems: The Case Of Water Clusters, Berhane Temelso, George Shields
Berhane Temelso
The nature of vibrational anharmonicity has been examined for the case of small water clusters using second-order vibrational perturbation theory (VPT2) applied on second-order Møller–Plesset perturbation theory (MP2) potential energy surfaces. Using a training set of 16 water clusters (H2O)n=2–6,8,9 with a total of 723 vibrational modes, we determined scaling factors that map the harmonic frequencies onto anharmonic ones. The intermolecular modes were found to be substantially more anharmonic than intramolecular bending and stretching modes. Due to the varying levels of anharmonicity of the intermolecular and intramolecular modes, different frequency scaling factors for each region were necessary to achieve the …
Isoquinoline-Derivatized Tris(2-Pyridylmethyl)Amines As Fluorescent Zinc Sensors With Strict Zn2+/Cd2+ Selectivity, Shawn Burdette, Yuji Mikata, Keiko Kawata, Saaya Takeuchi, Kaori Nakanishi, Hideo Konno, Saori Itami, Keiko Yasuda, Satoshi Tamotsu
Isoquinoline-Derivatized Tris(2-Pyridylmethyl)Amines As Fluorescent Zinc Sensors With Strict Zn2+/Cd2+ Selectivity, Shawn Burdette, Yuji Mikata, Keiko Kawata, Saaya Takeuchi, Kaori Nakanishi, Hideo Konno, Saori Itami, Keiko Yasuda, Satoshi Tamotsu
Shawn C. Burdette
Tris(2-pyridylmethyl)amine-based fluorescent ligands, N,N-bis(1-isoquinolylmethyl)-2-pyridylmethylamine (1-isoBQPA) and N,N-bis(7-methoxy-1-isoquinolylmethyl)-2-pyridylmethylamine (7-MeO-1-isoBQPA), have been prepared and the Zn2+-induced fluorescence enhancement has been investigated. Upon excitation at 324 nm, 1-isoBQPA exhibits a very weak emission (ϕ = [similar]0.010) in DMF–H2O (1 : 1). Upon Zn2+ addition, the 1-isoBQPA fluorescence increases (ϕZn = 0.055) at 357 nm and 464 nm. The fluorescence enhancement at longer wavelengths is Zn2+-specific, whereas Cd2+ induces a small emission increase at 464 nm (ICd/I0 = 1.1, ICd/IZn = 14%). The Zn2+/Cd2+ selectivity of the fluorescent response correlates with the Cd–Nisoquinoline and Zn–Nisoquinoline bond distances measured in the crystal structures. Introduction of …
Bis(2-Quinolylmethyl)Ethylenediaminediacetic Acids (Bqendas), Tqen–Edta Hybrid Molecules As Fluorescent Zinc Sensors, Shawn Burdette, Yju Mikata, Saaya Takeuchi, Hideo Konno, Satoshi Iwatsuki, Sakiko Akaji, Ikuko Hamagami, Masato Aoyama, Keiko Yasuda, Satoshi Tamotsu
Bis(2-Quinolylmethyl)Ethylenediaminediacetic Acids (Bqendas), Tqen–Edta Hybrid Molecules As Fluorescent Zinc Sensors, Shawn Burdette, Yju Mikata, Saaya Takeuchi, Hideo Konno, Satoshi Iwatsuki, Sakiko Akaji, Ikuko Hamagami, Masato Aoyama, Keiko Yasuda, Satoshi Tamotsu
Shawn C. Burdette
Molecular hybrids of TQEN (N,N,N′,N′-tetrakis(2-quinolylmethyl)ethylenediamine) and EDTA (ethylenediamine-N,N,N′,N′-tetraacetic acid) were examined as fluorescent Zn2+ sensors. Upon the addition of Zn2+, N,N-BQENDA (N,N-bis(2-quinolylmethyl)ethylenediamine-N′,N′-diacetic acid, 1a) exhibits a 30-fold emission enhancement at 456 nm (λex = 315 nm, ϕZn = 0.018) in buffer (HEPES, pH = 7.5, 100 mM KCl). The fluorescence enhancement is Zn2+-specific as Cd2+ induces much smaller increases (ICd/I0 = 5 and ICd/IZn = 16%). These spectroscopic properties, as well as the excellent water-solubility, represent a significant improvement compared to the parent TQEN sensor (ϕZn = 0.007, ICd/IZn = 64%). The isoquinoline analog N,N-1-isoBQENDA (N,N-bis(1-isoquinolylmethyl)ethylenediamine-N′,N′-diacetic acid, 1b) possesses a …