Mononuclear Iron(III) Complexes as Functional Models of Catechol Oxidases and Catalases

2015 ◽  
Vol 2015 (21) ◽  
pp. 3478-3484 ◽  
Author(s):  
Elena Badetti ◽  
Blerina Gjoka ◽  
Eszter Márta Nagy ◽  
Gérald Bernardinelli ◽  
Peter E. Kündig ◽  
...  
Keyword(s):  
Mononuclear Iron ◽  
Functional Models

scholarly journals Comparison of Nonheme Manganese- and Iron-Containing Flavone Synthase Mimics

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3220
Author(s):  
Dóra Lakk-Bogáth ◽  
Natalija Pantalon Juraj ◽  
Bashdar I. Meena ◽  
Berislav Perić ◽  
Srećko I. Kirin ◽  
...  
Keyword(s):  
Antioxidant Activities ◽  
Enzyme Reaction ◽  
Biological Processes ◽  
Mononuclear Iron ◽  
Functional Models ◽  
Wide Range ◽  
Metal Cofactor ◽  
Flavone Synthase ◽  
High Valent ◽  
Insight Into

Heme and nonheme-type flavone synthase enzymes, FS I and FS II are responsible for the synthesis of flavones, which play an important role in various biological processes, and have a wide range of biomedicinal properties including antitumor, antimalarial, and antioxidant activities. To get more insight into the mechanism of this curious enzyme reaction, nonheme structural and functional models were carried out by the use of mononuclear iron, [FeII(CDA-BPA*)]2+ (6) [CDA-BPA = N,N,N’,N’-tetrakis-(2-pyridylmethyl)-cyclohexanediamine], [FeII(CDA-BQA*)]2+ (5) [CDA-BQA = N,N,N’,N’-tetrakis-(2-quinolilmethyl)-cyclohexanediamine], [FeII(Bn-TPEN)(CH3CN)]2+ (3) [Bn-TPEN = N-benzyl-N,N’,N’-tris(2-pyridylmethyl)-1,2- diaminoethane], [FeIV(O)(Bn-TPEN)]2+ (9), and manganese, [MnII(N4Py*)(CH3CN)]2+ (2) [N4Py* = N,N-bis(2-pyridylmethyl)-1,2-di(2-pyridyl)ethylamine)], [MnII(Bn-TPEN)(CH3CN)]2+ (4) complexes as catalysts, where the possible reactive intermediates, high-valent FeIV(O) and MnIV(O) are known and well characterised. The results of the catalytic and stoichiometric reactions showed that the ligand framework and the nature of the metal cofactor significantly influenced the reactivity of the catalyst and its intermediate. Comparing the reactions of [FeIV(O)(Bn-TPEN)]2+ (9) and [MnIV(O)(Bn-TPEN)]2+ (10) towards flavanone under the same conditions, a 3.5-fold difference in reaction rate was observed in favor of iron, and this value is three orders of magnitude higher than was observed for the previously published [FeIV(O)(N2Py2Q*)]2+ [N,N-bis(2-quinolylmethyl)-1,2-di(2-pyridyl)ethylamine] species.

An insight to the noncovalent interactions in two triamine based mononuclear iron(III) Schiff base complexes with special emphasis on the formation of Br•••π halogen bonding

CrystEngComm ◽  
2021 ◽  
Author(s):  
Shouvik Chattopadhyay ◽  
Tanmoy Basak ◽  
Antonio Frontera
Keyword(s):  
Schiff Base ◽  
Solid State ◽  
Noncovalent Interactions ◽  
Halogen Bonding ◽  
Schiff Base Complexes ◽  
X Ray ◽  
Mononuclear Iron

Two mononuclear iron(III) complexes, [FeL1Cl]∙CH3CN (1) and [FeL2(N3)] (2) {H2L1= N,N′-bis(5-chlorosalicylidene)diethylenetriamine and H2L2= N,N′-bis(5-bromosalicylidene)diethylenetriamine}, have been synthesized and characterized by X-ray crystallographic studies. In the solid state, there are strong...

scholarly journals Precise point positioning with GPS and Galileo broadcast ephemerides

GPS Solutions ◽  
2021 ◽  
Vol 25 (2) ◽  
Author(s):  
Luca Carlin ◽  
André Hauschild ◽  
Oliver Montenbruck
Keyword(s):  
Precise Point Positioning ◽  
Three Dimensional ◽  
Test Results ◽  
Process Noise ◽  
Functional Models ◽  
Ambiguity Estimation ◽  
Point Positioning ◽  
And Performance ◽  
Range Error ◽  
Space Range

AbstractFor more than 20 years, precise point positioning (PPP) has been a well-established technique for carrier phase-based navigation. Traditionally, it relies on precise orbit and clock products to achieve accuracies in the order of centimeters. With the modernization of legacy GNSS constellations and the introduction of new systems such as Galileo, a continued reduction in the signal-in-space range error (SISRE) can be observed. Supported by this fact, we analyze the feasibility and performance of PPP with broadcast ephemerides and observations of Galileo and GPS. Two different functional models for compensation of SISREs are assessed: process noise in the ambiguity states and the explicit estimation of a SISRE state for each channel. Tests performed with permanent reference stations show that the position can be estimated in kinematic conditions with an average three-dimensional (3D) root mean square (RMS) error of 29 cm for Galileo and 63 cm for GPS. Dual-constellation solutions can further improve the accuracy to 25 cm. Compared to standard algorithms without SISRE compensation, the proposed PPP approaches offer a 40% performance improvement for Galileo and 70% for GPS when working with broadcast ephemerides. An additional test with observations taken on a boat ride yielded 3D RMS accuracy of 39 cm for Galileo, 41 cm for GPS, and 27 cm for dual-constellation processing compared to a real-time kinematic reference solution. Compared to the use of process noise in the phase ambiguity estimation, the explicit estimation of SISRE states yields a slightly improved robustness and accuracy at the expense of increased algorithmic complexity. Overall, the test results demonstrate that the application of broadcast ephemerides in a PPP model is feasible with modern GNSS constellations and able to reach accuracies in the order of few decimeters when using proper SISRE compensation techniques.

Combining Registration and Fitting for Functional Models

2008 ◽  
Vol 103 (483) ◽  
pp. 1155-1165 ◽  
Author(s):  
Alois Kneip ◽  
James O Ramsay
Keyword(s):  
Functional Models
Sign in / Sign up

Export Citation Format

Share Document