Progress and design challenges for high-spin molecules

2010 ◽  
Vol 83 (1) ◽  
pp. 141-149 ◽  
Author(s):  
Martin T. Lemaire
Keyword(s):  
Free Radical ◽  
Metal Complexes ◽  
High Spin ◽  
Critical Review ◽  
Mixed Valence ◽  
Double Exchange ◽  
Stable Free Radical ◽  
The Past ◽  
Molecule Design ◽  
Design Challenges

In this short critical review, selected examples of current (within the past two years) synthetic efforts toward the construction of high-spin molecules are explored, including the use of metal complexes containing stable free radical ligands, lanthanide or actinide complexes, and other coordination clusters, or a completely different approach, taking advantage of non-Heisenberg exchange in fully delocalized mixed-valence complexes (spin-dependent delocalization, SDD, or double exchange). A description of reported work in this regard is followed by a brief general discussion that highlights what the future may hold for high-spin molecule design.

scholarly journals Antifungal and Antioxidant Activities of Pyrrolidone Thiosemicarbazone Complexes

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Ahmed A. Al-Amiery ◽  
Abdul Amir H. Kadhum ◽  
Abu Bakar Mohamad
Keyword(s):  
Free Radical ◽  
Metal Complexes ◽  
Antioxidant Activities ◽  
Radical Scavenging ◽  
Molecular Structures ◽  
Molecular Orbital Calculations ◽  
Stable Free Radical ◽  
Thiosemicarbazone Complexes ◽  
Radical Scavenging Ability ◽  
Optimized Geometries

Metal complexes of (Z)-2-(pyrrolidin-2-ylidene)hydrazinecarbothioamide (L) with Cu(II), Co(II), and Ni(II) chlorides were tested against selected types of fungi and were found to have significant antifungal activities. The free-radical-scavenging ability of the metal complexes was determined by their interaction with the stable free radical 2,2′′-diphenyl-1-picrylhydrazyl, and all the compounds showed encouraging antioxidant activities. DFT calculations of the Cu complex were performed using molecular structures with optimized geometries. Molecular orbital calculations provide a detailed description of the orbitals, including spatial characteristics, nodal patterns, and the contributions of individual atoms.

Organic Free Radical and Metal Complexes. 2,2-Diphenyl-1-picrylhydrazyl with Cu(I)

1972 ◽  
Vol 50 (7) ◽  
pp. 999-1004 ◽  
Author(s):  
F. Leh ◽  
J. K. S. Wan
Keyword(s):  
Free Radical ◽  
Metal Complexes ◽  
Electron Donor ◽  
Organic Radical ◽  
Spectroscopic Methods ◽  
Stable Free Radical ◽  
Donor Ligand ◽  
Organic Free Radical

Reactions of Cu(I)Cl, Cu(II)Cl2, Cu(II) acetylacetonates, and Cu(II) N-methylsalicylalidiiminate with the stable free radical 2,2-diphenyl-1-picrylhydrazyl have been investigated. In all cases Cu(II) was reduced and the organic radical behaved as an electron donor-ligand to form complexes containing Cu(I). These novel free radical Cu(I) complexes were characterized by various spectroscopic methods, including e.s.r.

scholarly journals Synthesis, Characterization, Antimicrobial, DNA Cleavage, and Antioxidant Studies of Some Metal Complexes Derived from Schiff Base Containing Indole and Quinoline Moieties

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Mahendra Raj Karekal ◽  
Vivekanand Biradar ◽  
Mruthyunjayaswamy Bennikallu Hire Mathada
Keyword(s):  
Schiff Base ◽  
Free Radical ◽  
Metal Complexes ◽  
Dna Cleavage ◽  
Radical Scavenging Activity ◽  
Analytical Data ◽  
Radical Scavenging ◽  
Tridentate Ligand ◽  
Spectral Studies ◽  
Stable Free Radical

A new Schiff base of 5-chloro-3-phenyl-1H-indole-2-carboxyhydrazide and 3-formyl-2-hydroxy-1H-quinoline (HL), and its Cu(II), Co(II), Ni(II), Zn(II), Cd(II), and Hg(II) complexes have been synthesized and characterized in the light of microanalytical, IR,H1NMR, UV-Vis, FAB-mass, ESR, XRD, and TGA spectral studies. The magnetic susceptibility measurements and low conductivity data provide evidence for monomeric and neutral nature of the complexes. On the basis of spectral studies and analytical data, it is evident that the Schiff base acts as tridentate ligand. The Cu(II), Co(II), and Ni(II) complexes were octahedral, whereas Zn(II), Cd(II), and Hg(II) complexes were tetrahedral in nature. The redox behavior of the Cu(II) complex was investigated by electrochemical method using cyclic voltammetry. In order to evaluate the effect of metal ions upon chelation, both the ligand and its metal complexes were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleavage experiment performed using agarose gel electrophoresis method showed the cleavage of DNA by all the metal complexes. The free radical scavenging activity of newly synthesized compounds has been determined at a different concentration range by means of their interaction with the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH).

Heisenberg and double exchange in iron mixed valence [Fe6S6]+ supercluster

1997 ◽  
Vol 90 (3) ◽  
pp. 445-463 ◽  
Author(s):  
M. CZERWINSKI ◽  
J. DĄBROWSKI
Keyword(s):  
Mixed Valence ◽  
Double Exchange

Esr Indication of Heavy Metal Contamination of Urban Atmosphere

1993 ◽  
Vol 27 (7-8) ◽  
pp. 263-269 ◽  
Author(s):  
B. Iosefzon-Kuyavskaya ◽  
N. Myrlyan ◽  
A. Shames
Keyword(s):  
Heavy Metal ◽  
Air Pollution ◽  
Electron Spin Resonance ◽  
Free Radical ◽  
Metal Contamination ◽  
Heavy Metal Contamination ◽  
Urban Atmosphere ◽  
Stable Free Radical ◽  
Spin Resonance ◽  
Line Characteristic

Electron Spin Resonance (ESR) was used for the examination oi dust samples collected from snow in an urban area. On the main doublet ESR line attributed to the signal of paramagnetic metals, a singlet line characteristic for stable free radical centers (FRC) was observed. A negative correlation of significant level between FRC signal intensity and heavy metal (HM) content was established. It was shown that FRC line intensity of dust may be used as a surrogate parameter for the estimation of air pollution by HM.

scholarly journals Microwave-Assisted Synthesis, Characterization, Antimicrobial and Antioxidant Activity of Some New Isatin Derivatives

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
G. Kiran ◽  
T. Maneshwar ◽  
Y. Rajeshwar ◽  
M. Sarangapani
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Radical Scavenging ◽  
Microwave Assisted Synthesis ◽  
Stable Free Radical ◽  
Ft Ir ◽  
Antimicrobial And Antioxidant Activity ◽  
New Compounds ◽  
Isatin Derivatives

A series of β-Isatin aldehyde-N,N′-thiocarbohydrazone derivatives were synthesized and assayed for theirin vitroantimicrobial and antioxidant activity. The new compounds were characterized based on spectral (FT-IR, NMR, MS) analyses. All the test compounds possessed a broad spectrum of activity having MIC values rangeing from 12.5 to 400 μg/ml against the tested microorganisms. Among the compounds3e,3jand3nshow highest significant antimicrobial activity. The free radical scavenging effects of the test compounds against stable free radical DPPH (α,α-diphenyl-β-picryl hydrazyl) and H2O2were measured spectrophotometrically. Compounds3j,3n,3l, and3e, respectively, had the most effective antioxidant activity against DPPH and H2O2scavenging activity.

scholarly journals Unprecedented Coordination-Induced Bright Red Emission from Group 12 Metal-Bound Triarylazoimidazoles

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1739
Author(s):  
Artyom A. Astafiev ◽  
Olga V. Repina ◽  
Boris S. Tupertsev ◽  
Alexey A. Nazarov ◽  
Maria R. Gonchar ◽  
...  
Keyword(s):  
Visible Light ◽  
Metal Complexes ◽  
Scientific Literature ◽  
Photo Luminescence ◽  
Red Emission ◽  
The Past ◽  
Highly Efficient ◽  
Luminescence Emission ◽  
New Family ◽  
Group 12

Arylazoimidazoles are important dyes which were intensively studied in the past. In contrast, triarylazoimidazoles (derivatives which carry aryl substituents at the imidazole core) received almost no attention in the scientific literature. Here, we report a new family of simple and easily accessible triarylazoimidazole-group 12 metal complexes, which feature highly efficient photo-luminescence emission (Φ up to  0.44). Novel compounds exhibit bright red emission in solution, which could be excited with a visible light.

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