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Articles 1 - 8 of 8
Full-Text Articles in Chemistry
Benzothiadiazoles And Dipyrrolyl Quinoxalines With Extended Conjugated Chromophores-Fluorophores And Anion Sensors, Dmitry Aldakov, Manuel A. Palacios, Pavel Anzenbacher Jr.
Benzothiadiazoles And Dipyrrolyl Quinoxalines With Extended Conjugated Chromophores-Fluorophores And Anion Sensors, Dmitry Aldakov, Manuel A. Palacios, Pavel Anzenbacher Jr.
Chemistry Faculty Publications
Stable fluorescent chromophores find use in a growing number of practical applications, including their utility as laser dyes,1 emitters in light-emitting diodes,2 photoconductors,3 optical data storage,4 and optical switches.5 Stable fluorophores with high quantum yields are widely used in fluorescent sensors6 and labels.7 These became very popular lately, owing to their potential for high sensitivity at low concentration coupled with decreased cost of the required equipment.8 Recently, we have described a new class of fluorescent anion sensors bearing extended conjugated chromophores9 with incorporated 2,3-di(1H-2-pyrrolyl)quinoxaline, (DPQ), as the anion recognition element.10 Literature shows that DPQ binds anions via hydrogen bonding between …
Interaction Of Porphyrins With A Dendrimer Template: Self-Aggregation Controlled By Ph, Pavel Kubat, Kamil Lang, Pavel Janda, Pavel Anzenbacher Jr.
Interaction Of Porphyrins With A Dendrimer Template: Self-Aggregation Controlled By Ph, Pavel Kubat, Kamil Lang, Pavel Janda, Pavel Anzenbacher Jr.
Chemistry Faculty Publications
The interaction between self-aggregated porphyrins such as 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) and 5,10,15,20-tetrakis(4-phosphonatophenyl)porphyrin (TPPP), and a generation 5 (G5) PAMAM dendrimer template is governed by minute differences of porphyrin acido-basic properties. While at neutral pH both monomeric TPPS and TPPP form complexes with G5, decreasing pH did not lead to porphyrin ring protonation (pK(a) approximate to 5) but rather to the preferential formation of H-aggregates (probably H-dimers), most likely due to protonation of the G5. Upon further acidification of the solution, this face-to-face orientation of the porphyrin units is being converted to edge-to-edge aligned J-aggregates with a tightly defined structure. This process …
Simple Electrooptical Sensors For Inorganic Anions, Pavel Anzenbacher Jr., Karolina Jursikova, Manuel Marquez
Simple Electrooptical Sensors For Inorganic Anions, Pavel Anzenbacher Jr., Karolina Jursikova, Manuel Marquez
Chemistry Faculty Publications
Electrooptical sensors consisting of a conjugated chromophore undergoing a change in color and a redox-active moiety such as quinone fused to the chromophore were synthesized. Strong changes in colorimetric and electrochemical properties were observed in the presence of inorganic anions. A unique anion-specific response was observed for fluoride, pyrophosphate, and acetate. DFT (B3LYP/6-31G*) calculations performed for both "on/off" states of a sensor-fluoride model are in good agreement with the observed electrochemical and spectroscopic data.
Cu(I) Luminescence From The Tetranuclear Cu4s4 Cofactor Of A Synthetic 4-Helix Bundle, Olesya A. Kharenko, David C. Kennedy, Borries Demeler, Michael J. Maroney, Michael Y. Ogawa
Cu(I) Luminescence From The Tetranuclear Cu4s4 Cofactor Of A Synthetic 4-Helix Bundle, Olesya A. Kharenko, David C. Kennedy, Borries Demeler, Michael J. Maroney, Michael Y. Ogawa
Chemistry Faculty Publications
The addition of Cu(I) to the random-coil peptide, C16C19-GGY, produces a self-organized, metal-bridged 4-helix bundle which displays an intense room-temperature luminescence at 600 nm. Emission, UV, and CD titrations along with X-ray absorption studies indicate that the luminescent cofactor is likely a Cu4S4 cluster in which each Cu atom is bridged by the side chains of two cysteine residues and has terminal N/O ligation.
Sensing Of Antipyretic Carboxylates By Simple Chromogenic Calix[4]Pyrroles, Ryuhei Nishiyabu, Pavel Anzenbacher Jr.
Sensing Of Antipyretic Carboxylates By Simple Chromogenic Calix[4]Pyrroles, Ryuhei Nishiyabu, Pavel Anzenbacher Jr.
Chemistry Faculty Publications
We present a simple, two- or three-step method for the synthesis of chromogenic octamethylcalix[4]pyrrole-based (OMCP) sensors for anions. Electrophilic aromatic substitution allows for converting the pyrrole moieties of OMCP into a dye. The formation of a sensor-anion complex results in partial charge transfer and a dramatic change in color. The absorption (UV-vis) and NMR titration experiments show that the chromogenic OMCPs sense anions administered as aqueous solutions, even at high ionic strength ( approximately 0.1 M NaCl), while displaying selectivity for pyrophosphate and carboxylate anions. The experiments with polyurethane sensor films show a strong response for aqueous carboxylates, such as …
Hinge-Like Motions In Rna Kink-Turns: The Role Of The Second A-Minor Motif And Nominally Unpaired Bases, Neocles B. Leontis, Filip Rázga, Jaroslav Koča, Jiří Šponer
Hinge-Like Motions In Rna Kink-Turns: The Role Of The Second A-Minor Motif And Nominally Unpaired Bases, Neocles B. Leontis, Filip Rázga, Jaroslav Koča, Jiří Šponer
Chemistry Faculty Publications
Kink-turn (K-turn) motifs are asymmetric internal loops found at conserved positions in diverse RNAs, with sharp bends in phosphodiester backbones producing V-shaped structures. Explicit-solvent molecular dynamics simulations were carried out for three K-turns from 23S rRNA, i. e., Kt-38 located at the base of the A-site. nger, Kt-42 located at the base of the L7/L12 stalk, and Kt-58 located in domain III, and for the K-turn of human U4 snRNA. The simulations reveal hinge-like K-turn motions on the nanosecond timescale. The first conserved A-minor interaction between the K-turn stems is entirely stable in all simulations. The angle between the helical …
Green Photoluminescence From Platinum(Ii) Complexes Bearing Silylacetylide Ligands, Fei Hua, Solen Kinayyigit, John R. Cable, Felix Castellano
Green Photoluminescence From Platinum(Ii) Complexes Bearing Silylacetylide Ligands, Fei Hua, Solen Kinayyigit, John R. Cable, Felix Castellano
Chemistry Faculty Publications
The synthesis, structural characterization, photoluminescence properties, and density functional theory analysis of three Pt(II) diimine complexes, Pt(dbbpy)(CdropCR)(2) [dbbpy = 4,4'-di(tert-butyl-2,2'-bipyridine; R = -SiMe3, -CdropC-SiMe3, or -t-Bu], are presented. The Pt(dbbpy)(CdropC-tBu)(2) complex serves as a carbon-based ligand structure for which the photophysical properties of the two silicon-bearing complexes are compared in dichloromethane. Pt(dbbpy)(CdropC-SiMe3)(2) and Pt(dbbpy)(CdropC-CdropC-SiMe3)(2) display visible absorptions with strong green emission (lambda(emmax) = 526 and 524 nm, respectively) while Pt(dbbpy)(CdropCt-Bu)(2) displays efficient, long-lived yellow emission (lambda(emmax) = 557 nm). Direct side by side comparisons of Pt(dbbpy)(CdropC-SiMe3)(2) and Pt(dbbpy)(CdropC-t-Bu)(2) suggest that the difference in excited state energy results from the relative …
Recurrent Structural Rna Motifs, Isostericity Matrices And Sequence Alignments, Neocles B. Leontis, Aurélie Lescoute, Christian Massire, Eric Westhof
Recurrent Structural Rna Motifs, Isostericity Matrices And Sequence Alignments, Neocles B. Leontis, Aurélie Lescoute, Christian Massire, Eric Westhof
Chemistry Faculty Publications
The occurrences of two recurrent motifs in ribosomal RNA sequences, the Kink-turn and the C-loop, are examined in crystal structures and systematically compared with sequence alignments of rRNAs from the three kingdoms of life in order to identify the range of the structural and sequence variations. Isostericity Matrices are used to analyze structurally the sequence variations of the characteristic non-Watson-Crick base pairs for each motif. We show that Isostericity Matrices for non-Watson-Crick base pairs provide important tools for deriving the sequence signatures of recurrent motifs, for scoring and refining sequence alignments, and for determining whether motifs are conserved throughout evolution. …