Calculation of "Dewar" resonance energies in conjugated organic molecules

1969 ◽  
Vol 47 (19) ◽  
pp. 3535-3538 ◽  
Author(s):  
N. C. Baird
Keyword(s):  
Organic Compounds ◽  
Organic Molecules ◽  
Resonance Energy ◽  
Heats Of Formation ◽  
Conjugated Organic Molecules ◽  
Resonance Energies ◽  
Definition Of

Dewar's recent definition of resonance energy (1) for hydrocarbons is extended to molecules containing oxygen, and resonance energy values are calculated from experimental heats of formation for a variety of conjugated organic compounds. A simple additivity scheme is proposed whereby resonance energies and heats of formation can be accurately estimated for benzenoid systems.

Adsorption of Vapours of Some Organic Compounds on Surface of Iron-Substituted Layered Vanadyl Phosphate

2000 ◽  
Vol 65 (1) ◽  
pp. 47-57 ◽  
Author(s):  
Pavel Hradil ◽  
Jiří Votinský ◽  
Karel Komárek ◽  
Vítězslav Zima ◽  
Jaroslava Kalousová ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Organic Molecules ◽  
Ferric Ions ◽  
Vanadyl Phosphate ◽  
Enthalpy Of Adsorption ◽  
Adsorbent Surface ◽  
Specific Retention Volumes ◽  
Specific Retention ◽  
Retention Volumes ◽  
Chromatographic Measurement

Gas chromatographic measurement of specific retention volumes of vapours of selected groups of organic compounds has been used to determine differential molar enthalpy of adsorption of their molecules on the surface of layered vanadyl phosphate substituted with ferric ions having the composition of [Fe(H2O)]0.20(VO)0.80PO4. Various types of bonds of the molecules to the surface of the layered adsorbent including their probable orientation with respect to the layers have been discussed. It was observed a dependence of the specific peak elution volume and shape of chromatographic peak on the sample size in the cases of those compounds whose molecules are chemically bound to the adsorbent surface. A connection is pointed out between the adsorption strength of the organic molecules on the layered adsorbent and the tendency of the system to undergo intercalation reaction.

Heats of formation of organic molecules byAb Initio calculations: Carboxylic acids and esters

1992 ◽  
Vol 13 (7) ◽  
pp. 838-841 ◽  
Author(s):  
Norman L. Allinger ◽  
Lawrence R. Schmitz ◽  
Ioan Motoc ◽  
Charles Bender ◽  
Jan K. Labanowski
Keyword(s):  
Carboxylic Acids ◽  
Organic Molecules ◽  
Heats Of Formation

scholarly journals An investigation of the interrelationships between linear and nonlinear polarizabilities and bond-length alternation in conjugated organic molecules

1993 ◽  
Vol 90 (23) ◽  
pp. 11297-11301 ◽  
Author(s):  
C B Gorman ◽  
S R Marder
Keyword(s):  
Bond Length ◽  
Organic Molecules ◽  
Computational Method ◽  
Bond Length Alternation ◽  
Conjugated Molecules ◽  
Conjugated Organic Molecules ◽  
Alpha Beta ◽  
Relationship Of ◽  
The Relationship ◽  
Observable Parameter

A computational method was devised to explore the relationship of charge separation, geometry, molecular dipole moment (mu), polarizability (alpha), and hyperpolariz-abilities (beta, gamma) in conjugated organic molecules. We show that bond-length alternation (the average difference in length between single and double bonds in the molecule) is a key structurally observable parameter that can be correlated with hyperpolarizabilities and is thus relevant to the optimization of molecules and materials. By using this method, the relationship of bond-length alternation, mu, alpha, beta, and gamma for linear conjugated molecules is illustrated, and those molecules with maximized alpha, beta, and gamma are described.

Influence of conjugation length on ultrafast electronic tunneling in organic semiconductor thin films

2018 ◽  
Vol 20 (38) ◽  
pp. 25085-25095 ◽  
Author(s):  
Vincent V. Duong ◽  
Alexander L. Ayzner
Keyword(s):  
Molecular Electronics ◽  
Organic Molecules ◽  
Electron Delocalization ◽  
Conjugation Length ◽  
Conjugated Organic Molecules ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Semiconductor Thin Films ◽  
Electronic Tunneling ◽  
Rate Limiting

Electron delocalization in conjugated organic molecules is a rate-limiting step in maximizing the photo conversion efficiency of next generation photovoltaics and molecular electronics.

Chemical sensors based on π-conjugated organic molecules and gold nanoparticles

2009 ◽  
Vol 52 (6) ◽  
pp. 715-730 ◽  
Author(s):  
MingJian Yuan ◽  
YongJun Li ◽  
HuiBiao Liu ◽  
YuLiang Li
Keyword(s):  
Gold Nanoparticles ◽  
Chemical Sensors ◽  
Organic Molecules ◽  
Conjugated Organic Molecules

scholarly journals The Surface Properties of Calcite: An Adsorption Model with Orbital Control

2001 ◽  
Vol 19 (3) ◽  
pp. 237-244 ◽  
Author(s):  
Nikolai V. Nikolenko
Keyword(s):  
Surface Properties ◽  
Organic Compounds ◽  
Electron Donor ◽  
Organic Molecules ◽  
Orbital Interaction ◽  
Adsorption Model ◽  
Acceptor Interaction ◽  
Donor Acceptor ◽  
Correlation Parameters ◽  
Adsorptive Properties

The energies of unoccupied and occupied orbitals were used as the correlation parameters between the electronic and adsorptive properties of organic molecules. A model describing the chemisorption of organic compounds on CaCO3 involving two types of interaction, i.e. two-electron, donor–acceptor interaction HOMO(adsorbent) → LUMO(adsorbate) and four-electron, three-orbital interaction HOMO(adsorbent) → {LUMO(adsorbate) + HOMO(adsorbate)}, was proposed. It was concluded that strengthening of the bond involved in chemisorption occurred if the energies of the occupied orbitals associated with the adsorbate and adsorbent were concurrent.

Characterization of step-edge barrier crossing of para-sexiphenyl on the ZnO (101̄0) surface

2016 ◽  
Vol 18 (36) ◽  
pp. 25329-25341 ◽  
Author(s):  
Karol Palczynski ◽  
Philipp Herrmann ◽  
Georg Heimel ◽  
Joachim Dzubiella
Keyword(s):  
Thin Film ◽  
Mass Transport ◽  
Organic Molecules ◽  
Optoelectronic Devices ◽  
Thin Film Deposition ◽  
Essential Elements ◽  
Transport Processes ◽  
Film Deposition ◽  
Conjugated Organic Molecules

Mass transport processes of conjugated organic molecules (COMs) on inorganic surfaces are essential elements in thin film deposition for hybrid optoelectronic devices.

Search for molecular biosignatures on Mars: laboratory simulations of UV irradiation of molecule-mineral complexes

2021 ◽  
Author(s):  
Teresa Fornaro ◽  
Giovanni Poggiali ◽  
Maria Angela Corazzi ◽  
Cristina Garcia ◽  
Giulia Dimitri ◽  
...  
Keyword(s):  
Amino Acids ◽  
Organic Compounds ◽  
Uv Irradiation ◽  
Organic Molecules ◽  
Spectroscopic Characterization ◽  
Sample Return ◽  
Laboratory Simulations ◽  
Prebiotic Molecules

<div> </div> <p><strong>Abstract</strong></p> <p>We present laboratory activities of preparation, characterization, and UV irradiation processing of Mars soil analogues, which are key to support both in situ exploration and sample return missions devoted to detection of molecular biosignatures on Mars.</p> <p>In detail we prepared analog mineral samples relevant to the landing sites of past, present and future Mars exploration missions, such as Gale Crater, Jezero Crater, and Oxia Planum. We doped these samples with a large variety of organic molecules (both biotic and prebiotic molecules) like amino acids, nucleotides, monosaccharides, aldehydes, lipids. We investigated molecular photostability under UV irradiation by monitoring in situ possible modifications of infrared spectroscopic features. These investigations provide pivotal information for ground analysis carried out by rovers on Mars.</p> <p><strong>Introduction</strong></p> <p>Laboratory simulations of Mars are key to support the scientific activity and technology development of life detection instruments on board present and upcoming rover missions such as Mars2020 Perseverance [1] and ExoMars2022 Rosalind Franklin [2]. Studies about the stability of organic molecules in a Martian-like environment allow us to explore the conditions for the preservation of molecular biosignatures and develop models for their degradation in the Martian geological record. A systematic study of the effects of UV radiation on a variety of molecule-mineral complexes mimicking Martian soil can be key for the selection of the most interesting samples to analyse in situ or/and collect for sample return. Testing the sensitivity of different techniques for detection of the diagnostic features of molecular biosignatures embedded into mineral matrices as a function of the molecular concentration helps the choice, design and operation of flight instruments, as well as the interpretation of data collected on the ground during mission operative periods.</p> <p><strong>Methods</strong></p> <p>Experimental analyses were conducted in the Astrobiology Laboratory at INAF-Astrophysical Observatory of Arcetri (Firenze, Italy). Laboratory activities pertain to: (i) synthesis of Mars soil analogues doped with organic compounds that are considered potential molecular biosignatures; (ii) UV-irradiation processing of the Mars soil analogues under Martian-like conditions; and (iii) spectroscopic characterization of the Mars soil analogues.</p> <p><strong>Results</strong></p> <p>Such studies have shown to be very informative in identifying mineral deposits most suitable for preservation of organic compounds, while highlighting the complementarity of different techniques for biomarkers detection, which is critical for ensuring the success of space missions devoted to the search for signs of life on Mars.</p> <p>We will present a series of laboratory results on molecular degradation caused by UV on Mars and possible application to detection of organics by Martian rovers [3,4,5,6]. In detail, we investigated the photostability of several amino acids like glycine, alanine, methionine, valine, tryptophan, phenylalanine, glutamic acid, prebiotic molecules like urea, deoxyribose and glycolaldehyde, and biomarkers like nucleotides and phytane adsorbed on relevant Martian analogs. We monitored the degradation of these molecule-mineral complexes through in situ spectroscopic analysis, investigating the reflectance properties of the samples in the NIR/MIR spectral region. Such spectroscopic characterization of molecular alteration products provides support for two upcoming robotic missions to Mars that will employ NIR spectroscopy to look for molecular biosignatures, through the instruments SuperCam on board Mars 2020, ISEM, Ma_MISS and MicrOmega on board ExoMars 2022.</p> <p><strong>Acknowledgements</strong></p> <p>This research was supported by the Italian Space Agency (ASI) grant agreement ExoMars n. 2017-48-H.0.</p> <p><strong>References</strong></p> <p>[1] Farley K. A. et al. (2020) Space Sci. Rev. 216, 142.</p> <p>[2] Vago, J. L. et al. (2017) Astrobiology 6, 309–347.</p> <p>[3] Fornaro T. et al. (2013) Icarus 226, 1068–1085.</p> <p>[4] Fornaro T. et al. (2018) Icarus 313, 38-60.</p> <p>[5] Fornaro T. et al. (2020) Front. Astron. Space Sci. 7:539289.</p> <p>[6] Poggiali G. et al. (2020) Front. Astron. Space Sci. 7:18.</p>

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