FEW Chemicals GmbH

Bitterfeld-Wolfen, Germany

FEW Chemicals GmbH

Bitterfeld-Wolfen, Germany
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Mustroph H.,FEW Chemicals GmbH | Ernst S.,FEW Chemicals GmbH | Senns B.,FEW Chemicals GmbH | Towns A.D.,Vivimed Labs Europe Ltd
Coloration Technology | Year: 2015

The creation of the first synthetic dyes not only stimulated the hunt for new colorants but also drove the search for rules correlating the constitution of organic compounds with their colour. Dye chemistry additionally facilitated the development of molecular electronic spectroscopy as well as theories of molecular electronic structure and electronic transitions. Powerful quantum chemical computational tools are now available for the prediction of the electronic structure and spectroscopic characteristics of organic compounds. Such methods are thus useful in designing new functional colorants and aiding interpretation of their properties. However, without a deep appreciation of the principles and assumptions behind the calculations, one runs the risk of misunderstanding what can be achieved as well as becoming confused about how the outputted electronic and vibronic transition data correspond to observed absorption spectra. This review therefore aims to cover fundamentals of electronic spectroscopy that are often overlooked and enable the dye chemist using modern computational methods to comprehend the subtle differences in the types of transition energy value that such software can generate. In addition, the limitations of these methods in predicting absorption maxima and intensities of real-world colorants will be discussed in the context of physical influences on absorption band position and shape, for example from the perspective of different forms of the Franck-Condon principle. In essence, the goal of this review is to clarify, in terms that practical dye chemists will understand, what computational methods can predict and how valid these predictions are compared with reality. © 2015 Society of Dyers and Colourists.


Strehmel B.,Niederrhein University of Applied Sciences | Ernst S.,FEW Chemicals GmbH | Reiner K.,FEW Chemicals GmbH | Keil D.,FEW Chemicals GmbH | And 2 more authors.
Zeitschrift fur Physikalische Chemie | Year: 2014

This contribution discusses photoinitiated crosslinking of multifunctional acrylic esters in polymeric binders based on digital imaging using the Computer to Plate (CtP) technology applying laser exposure at 830 nm in the near infrared (NIR). All coating components (NIR photoinitiator system, monomers, binder, adhesion promoter, contrast dye, and oxygen barrier material) were applied as thin double layer film (1-2 μmdry film thickness) on Al-plateswith an anodized surface. Materials exposed exhibit a sensitivity between 30-200 mJ/cm2depending on the NIR-photoinitiator composition. This was processed in a weak aqueous alkaline bath to obtain the image. Generation of initiating radicals occurs by electron transfer from the excited state of the NIR-sensitizer to the radical generator; that is either an oniumsalt or neutral electron deficient compound. Redox potentials were determined for the NIR-sensitizers and the radical generator. These data allow a rough estimate regarding the free energy of electron transfer of the excited state of the sensitizer and radical generator in NIR-photosensitive imaging material. Photoinduced electron transfer plays a major function to generate initiating radicals by a sensitized mechanism but thermal events also influence sensitivity of the coating. Particular the non-radiative deactivation of the NIR-sensitizer possesses a major function to release selectively the heat. Absorption data of manyNIR-sensitizers used exhibitmolar extinction coefficient ofmore than 200 000M-1cm-1.


Grant
Agency: European Commission | Branch: FP7 | Program: BSG-SME | Phase: SME-1 | Award Amount: 1.43M | Year: 2009

There are 195 million households in Europe whose combined domestic heating needs account for 26% of Europes energy demand and 500 billion tonnes of CO2 emissions annually. Reducing this will be important if Europe is to achieve ambitious emission reduction targets, reduce its excessive reliance on imported energy and the decrease costs to households and industry. The most effective way to decentralise energy production is to increase the amount of generation at source, in this case within the home. A common barrier to the adoption of most energy saving technologies is the high initial investment cost which results in long payback periods considering current energy prices. However, with prices on the rise, existing technologies such as solar thermal heating systems and heat pumps are becoming increasingly popular. Although both are reasonably efficient, existing solar thermal heating systems generally only provide up to 60% of a typical households annual hot water demand. Air source heat pumps are more effective and can provide up to 100% of total household heating requirements but their performance decreases significantly in winter and they suffer from frost-build up. As these technologies are becoming commodity products, SMEs in these markets are coming under increasing pressure from cheap and often unreliable imports from Asia. It is therefore paramount that European SMEs keep a technological edge over these competitors. We therefore propose to develop a novel solar air source heat pump system which is 25% more efficient than a typical air source heat pump and 7% more efficient than a combination of a standard ASHP and a solar thermal system while only costing 60% of the combined price of these separate systems. The SOLARIS system will result in significant savings to the energy consumer, reduced CO2 emissions and a significant financial return to the SOLARIS supply chain.


Boom K.,Leibniz University of Hanover | Muller M.,Leibniz University of Hanover | Stein F.,Leibniz University of Hanover | Ernst S.,FEW Chemicals GmbH | Morgenstern K.,Ruhr University Bochum
Journal of Physical Chemistry C | Year: 2015

We investigate astraphloxine, an industrial dye, on two metal surfaces, Au(111) and Ag(111). Low-temperature scanning tunneling microscopy with submolecular resolution in comparison to semiempirical calculations reveal that only two of the nine possible conformers of this molecule are adsorbed. The two conformers adsorb via one of their indol groups, which serves as a platform that decouples the rest of the molecule from the surfaces. A change from one to the other conformer is demonstrated by injecting inelastic electrons from the tunneling tip selectively into individual molecules. © 2015 American Chemical Society.


The concept of a potential-energy surface (PES) is central to our understanding of spectroscopy, photochemistry, and chemical kinetics. However, the terminology used in connection with the basic approximations is variously, and somewhat confusingly, represented with such phrases as “adiabatic”, “Born–Oppenheimer”, or “Born–Oppenheimer adiabatic” approximation. Concerning the closely relevant and important Franck–Condon principle (FCP), the IUPAC definition differentiates between a classical and quantum mechanical formulation. Consequently, in many publications we find terms such as “Franck–Condon (excited) state”, or a vertical transition to the “Franck–Condon point” with the “Franck–Condon geometry” that relaxes to the excited-state equilibrium geometry. The Born–Oppenheimer approximation and the “classical” model of the Franck–Condon principle are typical examples of misused terms and lax interpretations of the original theories. In this essay, we revisit the original publications of pioneers of the PES concept and the FCP to help stimulate a lively discussion and clearer thinking around these important concepts. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


Schmitz C.,Niederrhein University of Applied Sciences | Halbhuber A.,Niederrhein University of Applied Sciences | Keil D.,FEW Chemicals GmbH | Strehmel B.,Niederrhein University of Applied Sciences
Progress in Organic Coatings | Year: 2016

Photoinitiated radical polymerization using as photoinitiator system a combination of NIR-sensitizer (Sens) and a radical initiator (RI) was investigated in different multifunctional monomers derived from the multifunctional acrylic esters HDDA, TPGDA, PEGDA, and TMPTA. NIR-LEDs were applied for exposure exhibiting their emission maximum either at 750nm, 790nm, 830nm or 940nm. Solubility of Sens in the respective monomers, their absorption data (λabs max, εmax), fluorescence data (Φf, λf max), electrochemical data (E ox, E red) and the free energy of electron transfer (δG el) between the excited state of Sens and RI were compiled. It showed for many systems an exothermic behavior, which does not always correlate with reactivity. Iodonium salts with low coordinating anions ([B(Ph)4]-, [B(Ph-F5)4]-, [(CF3SO2)2N]-, PF6 -) and Triazine A (2,4-Bis(trichloromethyl)-6-(4-methoxy)phenyl-1,3,5-triazine) were applied as RI. Sens was selected from the group of cyanines in which neutral compounds exhibited the highest reactivity. Cationic sensitizers showed almost no initiating reactivity. Furthermore, the sensitizer (5-(6-(2-(3-Ethyl-1,1-dimethyl-1H-benzo[e]indol-2(3H)-ylidene)ethylidene)-2-(2-(3-ethyl-1,1-dimethyl-1H-benzo[e]indol-3-ium-2-yl)vinyl)cyclohex-1-en-1-yl)-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-olate) (S9) was taken to study the effect of wavelength dependent LED excitation. The highest reactivity was found for the LED emitting at 850nm where the system possesses the highest excitation volume and the lowest absorption of photoproducts. Furthermore, thermal investigation approved that the combination S9 and iodonium salt can be considered as a thermal initiation system either. Thus, these systems can be seen as hybrid initiator systems. Finally, we show for the first time the generation of solvated protons using different iodonium salts and sensitizers in acetone as surrounding. The activity of solvated protons was evaluated showing a certain reactivity tendency. The number of solvated protons with respected to the number of sensitizer molecules was lower than unity showing their consumption by nucleophilic centers. © 2016 Elsevier B.V.


Mustroph H.,FEW Chemicals GmbH | Reiner K.,FEW Chemicals GmbH | Senns B.,FEW Chemicals GmbH | Mistol J.,FEW Chemicals GmbH | And 3 more authors.
Chemistry - A European Journal | Year: 2012

Two series of new merocyanine dyes have been synthesised and the dependence of their electronic structure on substituents and solvents has been studied by NMR spectroscopy, by using both the NMR 13C chemical shifts between adjacent C atoms in the polymethine chain and the 3J(H,H) coupling constants for trans-vicinal protons. The widely used valence bond (VB) model based on two contributing structures cannot account theoretically for the observed alternating π-electron density in the polymethine chain. In addition, the prediction of zero-π-bond order alternation (or zero-bond length alternation) by this model is also incorrect. However, the results are consistent with the predictions of a qualitative VB model which considers the resonance of a positive charge throughout the whole polymethine chain. Based on this model and the Franck-Condon principle the effect of substituents and solvents on the fine structure of the electronic spectra of these dyes can be explained as vibronic transitions from the vibrational state v=0 to v', where v is the vibrational quantum number of the totally symmetric C=C valence vibration of the polymethine chain in the electronic ground state and v' is that in the electronic excited state. In contrast, neither the effects of substituents or solvents on the electronic structure of merocyanines and their electronic spectra can be accounted for by the simple two state VB model. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


The quantum mechanical model is fully recognized and used for rotational and vibronic transitions in molecules, where according to the model, transitions occur between discrete, the resonance condition matching states, only. It is also accepted that selection rules are implied for rotational and vibronic transitions. Why is it so hard to recognize that this established quantum mechanical model is also valid for vibronic transitions, where the Franck-Condon principle instead of a selection rule applies to the population of vibronic states in the electronic excitation state? In any case, supposed illustrative and comfortable but wrong explanations, also if they are widely used, must not replace more sophisticated, correct quantum mechanical models. In scientific publications as well as in teaching only the quantum mechanical version of the Franck-Condon principle should be used. Terms like "Franck-Condon point" or "Franck-Condon region of the photochemical reaction" should be avoided in the future. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Mistol J.,FEW Chemicals GmbH | Ernst S.,FEW Chemicals GmbH | Keil D.,FEW Chemicals GmbH | Hennig L.,University of Leipzig
Dyes and Pigments | Year: 2015

Squaraines containing 2,3-dihydro-1H-perimidine terminal groups have been known since 1993. In the literature two structure types have been described; those involving bonding of the four-membered ring to C-4 and those involving bonding to C-6 of the dihydroperimidine unit. It was found by extensive application of one dimensional and two-dimensional nuclear magnetic resonance spectroscopic techniques, that the 2,3-dihydro-1H-perimidine terminal groups are linked at their 4-position with the four-membered cyclic ring, and not at their 6-position. It was also found by nuclear magnetic resonance spectroscopy that hindered rotation about the partial double bond between the 2,3-dihydro-1H-perimidine terminal groups and the central four membered cyclic ring, leads to a syn-anti isomerization of the dihydroperimidine derived squaraine dyes. This feature is confirmed by the detection of two isomers using 2nd order derivative ultraviolet-visible absorption spectroscopy. © 2015 Elsevier Ltd. All rights reserved.


Two series of new merocyanine dyes have been synthesised and the dependence of their electronic structure on substituents and solvents has been studied by NMR spectroscopy, by using both the NMR (13)C chemical shifts between adjacent C atoms in the polymethine chain and the (3)J(H,H) coupling constants for trans-vicinal protons. The widely used valence bond (VB) model based on two contributing structures cannot account theoretically for the observed alternating -electron density in the polymethine chain. In addition, the prediction of zero--bond order alternation (or zero-bond length alternation) by this model is also incorrect. However, the results are consistent with the predictions of a qualitative VB model which considers the resonance of a positive charge throughout the whole polymethine chain. Based on this model and the Franck-Condon principle the effect of substituents and solvents on the fine structure of the electronic spectra of these dyes can be explained as vibronic transitions from the vibrational state v = 0 to v, where v is the vibrational quantum number of the totally symmetric C=C valence vibration of the polymethine chain in the electronic ground state and v is that in the electronic excited state. In contrast, neither the effects of substituents or solvents on the electronic structure of merocyanines and their electronic spectra can be accounted for by the simple two state VB model.

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