Blue versus yellow emission in bipolar fluorenone derivatives: the impact of aggregation and hydrogen bonding

2018 ◽  
Vol 6 (7) ◽  
pp. 1679-1692 ◽  
Author(s):  
N. A. Kukhta ◽  
D. Volyniuk ◽  
J. V. Grazulevicius ◽  
G. Sini
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Blue Emission ◽  
Yellow Emission ◽  
The Impact ◽  
Bright Blue ◽  
Aromatic Hydrogen

Fluorenone derivatives demonstrate bright blue emission instead of yellow due to the disruption of the intermolecular CO⋯HC (aromatic) hydrogen bonds.

The impact on the ring related vibrational frequencies of pyridine of hydrogen bonds with haloforms – a topology perspective

2019 ◽  
Vol 21 (4) ◽  
pp. 1724-1736 ◽  
Author(s):  
Enrico Benassi ◽  
Kamila Akhmetova ◽  
Haiyan Fan
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Ring Structure ◽  
Vibrational Frequencies ◽  
Bonding System ◽  
Hydrogen Bonding System ◽  
The Impact

An intermolecular ring structure is identified for the hydrogen bonding system of pyridine and haloforms.

Blue Emitting BaAl2O4:Ce3+ Nanophosphors with High Color Purity and Brightness for White LEDs

2019 ◽  
Vol 25 (6) ◽  
pp. 1466-1470 ◽  
Author(s):  
Rituparna Chatterjee ◽  
Subhajit Saha ◽  
Karamjyoti Panigrahi ◽  
Uttam Kumar Ghorai ◽  
Gopes Chandra Das ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Field Emission ◽  
Sol Gel ◽  
Blue Emission ◽  
Diffraction Field ◽  
White Leds ◽  
Display Devices ◽  
Transmission Electron ◽  
Structure Morphology ◽  
The Impact

AbstractIn this work, strongly blue emitting Ce3+-activated BaAl2O4 nanophosphors were successfully synthesized by a sol–gel technique. The crystal structure, morphology, and microstructure of the nanophosphors have been studied by X-ray powder diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. The photoluminescence spectra show the impact of concentration variation of Ce3+ on the photoluminescence emission of the phosphor. These nanophosphors display intense blue emission peaking at 422 nm generated by the Ce3+ 5d → 4f transition under 350 nm excitation. Our results reveal that this nanophosphor has the capability to take part in the emergent domain of solid-state lighting and field-emission display devices.

scholarly journals Hydrogen Bonds: Raman Spectroscopic Study

2021 ◽  
Vol 22 (10) ◽  
pp. 5380
Author(s):  
Boris A. Kolesov
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Spectroscopic Study ◽  
Raman Spectra ◽  
Temperature Region ◽  
Vibrational Frequency ◽  
Chemical Compounds ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Proton Dynamics

The work outlines general ideas on how the frequency and the intensity of proton vibrations of X–H×××Y hydrogen bonding are formed as the bond evolves from weak to maximally strong bonding. For this purpose, the Raman spectra of different chemical compounds with moderate, strong, and extremely strong hydrogen bonds were obtained in the temperature region of 5 K–300 K. The dependence of the proton vibrational frequency is schematically presented as a function of the rigidity of O-H×××O bonding. The problems of proton dynamics on tautomeric O–H···O bonds are considered. A brief description of the N–H···O and C–H···Y hydrogen bonds is given.

scholarly journals Cooperation/Competition between Halogen Bonds and Hydrogen Bonds in Complexes of 2,6-Diaminopyridines and X-CY3 (X = Cl, Br; Y = H, F)

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 766
Author(s):  
Barbara Bankiewicz ◽  
Marcin Palusiak
Keyword(s):  
Complex Formation ◽  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Electrostatic Interactions ◽  
Dipole Moments ◽  
Main Role ◽  
Halogen Bonds ◽  
Topological Parameters ◽  
Leading Role ◽  
The Impact

The DFT calculations have been performed on a series of two-element complexes formed by substituted 2,6-diaminopyridine (R−PDA) and pyridine (R−Pyr) with X−CY3 molecules (where X = Cl, Br and Y = H, F). The primary aim of this study was to examine the intermolecular hydrogen and halogen bonds in the condition of their mutual coexistence. Symmetry/antisymmetry of the interrelation between three individual interactions is addressed. It appears that halogen bonds play the main role in the stabilization of the structures of the selected systems. However, the occurrence of one or two hydrogen bonds was associated with the favourable geometry of the complexes. Moreover, the impact of different substituent groups attached in the para position to the aromatic ring of the 2,6-diaminopyridine and pyridine on the character of the intermolecular hydrogen and halogen bonds was examined. The results indicate that the presence of electron-donating substituents strengthens the bonds. In turn, the presence of electron-withdrawing substituents reduces the strength of halogen bonds. Additionally, when hydrogen and halogen bonds lose their leading role in the complex formation, the nonspecific electrostatic interactions between dipole moments take their place. Analysis was based on geometric, energetic, and topological parameters of the studied systems.

2-Hydroxy-3-methoxybenzaldehyde (pyridinium-4-ylcarbonyl)hydrazone chloride hemihydrate

2006 ◽  
Vol 62 (5) ◽  
pp. o2043-o2044 ◽  
Author(s):  
Shao-Wen Chen ◽  
Han-Dong Yin ◽  
Da-Qi Wang ◽  
Xia Kong ◽  
Xiao-Fang Chen
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Compound C

The crystal structure of the title compound, C14H14ClN3O3 +·Cl−·0.5H2O, exhibits O—H...O, C—H...O, C—H...Cl, N—H...Cl and O—H...Cl hydrogen bonds. The chloride anions participate in extensive hydrogen bonding with the aminium cations and link molecules through multiple N—H+...Cl− interactions.

scholarly journals Small Changes: Using Assessment to Direct Instructional Practices in Large-Enrollment Biochemistry Courses

2017 ◽  
Vol 16 (1) ◽  
pp. ar7 ◽  
Author(s):  
Xiaoying Xu ◽  
Jennifer E. Lewis ◽  
Jennifer Loertscher ◽  
Vicky Minderhout ◽  
Heather L. Tienson
Keyword(s):  
Hydrogen Bonding ◽  
Student Performance ◽  
Bond Energy ◽  
Multiple Choice ◽  
Instructional Interventions ◽  
Student Responses ◽  
Large Classes ◽  
Instructional Effect ◽  
Large Enrollment ◽  
The Impact

Multiple-choice assessments provide a straightforward way for instructors of large classes to collect data related to student understanding of key concepts at the beginning and end of a course. By tracking student performance over time, instructors receive formative feedback about their teaching and can assess the impact of instructional changes. The evidence of instructional effectiveness can in turn inform future instruction, and vice versa. In this study, we analyzed student responses on an optimized pretest and posttest administered during four different quarters in a large-enrollment biochemistry course. Student performance and the effect of instructional interventions related to three fundamental concepts—hydrogen bonding, bond energy, and pKa—were analyzed. After instructional interventions, a larger proportion of students demonstrated knowledge of these concepts compared with data collected before instructional interventions. Student responses trended from inconsistent to consistent and from incorrect to correct. The instructional effect was particularly remarkable for the later three quarters related to hydrogen bonding and bond energy. This study supports the use of multiple-choice instruments to assess the effectiveness of instructional interventions, especially in large classes, by providing instructors with quick and reliable feedback on student knowledge of each specific fundamental concept.

Five pseudopolymorphs of 6-amino-2-thiouracil: absence of N—H...S hydrogen bonds

2012 ◽  
Vol 69 (1) ◽  
pp. 93-100 ◽  
Author(s):  
Wilhelm Maximilian Hützler ◽  
Michael Bolte
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Cambridge Structural Database ◽  
Hydrogen Bonding Pattern ◽  
Crystallization Experiments ◽  
Structural Database ◽  
Thiouracil Derivatives

In order to study the preferred hydrogen-bonding pattern of 6-amino-2-thiouracil, C4H5N3OS, (I), crystallization experiments yielded five different pseudopolymorphs of (I), namely the dimethylformamide disolvate, C4H5N3OS·2C3H7NO, (Ia), the dimethylacetamide monosolvate, C4H5N3OS·C4H9NO, (Ib), the dimethylacetamide sesquisolvate, C4H5N3OS·1.5C4H9NO, (Ic), and two different 1-methylpyrrolidin-2-one sesquisolvates, C4H5N3OS·1.5C5H9NO, (Id) and (Ie). All structures containR21(6) N—H...O hydrogen-bond motifs. In the latter four structures, additionalR22(8) N—H...O hydrogen-bond motifs are present stabilizing homodimers of (I). No type of hydrogen bond other than N—H...O is observed. According to a search of the Cambridge Structural Database, most 2-thiouracil derivatives form homodimers stabilized by anR22(8) hydrogen-bonding pattern, with (i) only N—H...O, (ii) only N—H...S or (iii) alternating pairs of N—H...O and N—H...S hydrogen bonds.

scholarly journals Two New Polyiodides in the 4,4´-Bipyridinium Diiodide/Iodine System

2012 ◽  
Vol 67 (1) ◽  
pp. 5-10
Author(s):  
Guido J. Reiss ◽  
Martin van Megen
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Complex I ◽  
The Other ◽  
Cyclic Dimer ◽  
Water Molecules ◽  
Spectroscopic Methods ◽  
Halogen Bonds ◽  
One Dimensional ◽  
Hydroiodic Acid

The reaction of bipyridine with hydroiodic acid in the presence of iodine gave two new polyiodide-containing salts best described as 4,4´-bipyridinium bis(triiodide), C10H10N2[I3]2, 1, and bis(4,4´-bipyridinium) diiodide bis(triiodide) tris(diiodine) solvate dihydrate, (C10H10N2)2I2[I3]2 · 3 I2 ·2H2O, 2. Both compounds have been structurally characterized by crystallographic and spectroscopic methods (Raman and IR). Compound 1 is composed of I3 − anions forming one-dimensional polymers connected by interionic halogen bonds. These chains run along [101] with one crystallographically independent triiodide anion aligned and the other triiodide anion perpendicular to the chain direction. There are no classical hydrogen bonds present in 1. The structure of 2 consists of a complex I144− anion, 4,4´-bipyridinium dications and hydrogen-bonded water molecules in the ratio of 1 : 2 : 2. The I144− polyiodide anion is best described as an adduct of two iodide and two triiodide anions and three diiodine molecules. Two 4,4´-bipyridinium cations and two water molecules form a cyclic dimer through N-H· · ·O hydrogen bonds. Only weak hydrogen bonding is found between these cyclic dimers and the polyiodide anions.

Sign in / Sign up

Export Citation Format

Share Document