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Silver-pyrazole complexes as hybrid multifunctional materials with metallomesogenic and photoluminescent behaviour.
MedLine Citation:
PMID:  23188455     Owner:  NLM     Status:  Publisher    
New pyridine-functionalised pyrazole compounds [Hpz(R(n)py)] (R(n) = C(6)H(4)OC(n)H(2n+1); n = 12, 14, 16, 18; ) and their corresponding silver complexes [Ag(Hpz(R(n)py))(2)][A] ([A] = NO(3)(-), BF(4)(-); ) have been synthesised and characterised. All of them, with the exception of , are liquid crystal materials exhibiting monotropic or enantiotropic SmA mesophases, in contrast to the non-mesomorphic related R(n)-monosubstituted compounds. Because the molecular shape is a factor determinant in the organisation of molecules in the liquid crystal phase, we were interested in solving the crystal structure of representative examples of the mentioned compounds, such as and . So, the X-ray crystal structure of [Hpz(R(12)py)] shows the presence of dimeric units through N-HN hydrogen bonds, which conform to an elongated molecular shape containing a double chain length. On the other hand, the structure of [Ag(Hpz(R(14)py))(2)][NO(3)] also evidenced Ag-Ag bonded dimers from 'U'-shaped cationic entities. These dimers exhibit four chains, two by two alternated, so giving rise to a longer molecular length. Of particular interest was to observe that in both structures, the dimers are layer-like packed, their lamellar structures being related to that of the mesophases found in both kinds of compounds. Furthermore, the analysis of the optical data of the compounds and and the silver compounds , , and as representative examples pointed out their luminescent behaviour as well as their good ability to act as fluorescent probes for Zn(2+), Cu(2+) and Ag(+). An increase in the fluorescence quantum yields is observed in the final complexes produced in the titrations, this fact being specially notable when was used as the starting compound.
Paloma Ovejero; Eduardo Asensio; José Vicente Heras; José Antonio Campo; Mercedes Cano; M Rosario Torres; Cristina Núñez; Carlos Lodeiro
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-11-28
Journal Detail:
Title:  Dalton transactions (Cambridge, England : 2003)     Volume:  -     ISSN:  1477-9234     ISO Abbreviation:  Dalton Trans     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101176026     Medline TA:  Dalton Trans     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Departamento de Química Inorgánica I, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid, Spain.
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