General Overview of Our Research

 

Molecular Thinking for Nanoplasmonic Design:

The development of nanoplasmonics has been tremendous during the past two decades, driven in part by the improvements in colloidal synthesis of nanocrystals and manipulation of nanoparticle surface functionalities. This has granted access not only to exquisite control over the morphology of nanoparticles but also to novel multiparticle nanostructures with a variety of organizational motifs. We are interested in the synthesis of plasmonic nanomaterials and the study of their corresponding properties and correlations with molecular concepts that have been around for a long time. Additional thinking along these lines may lead to further expansion of nanoplasmonics and to multiple surprising discoveries in this field (ACS Nano 2012, 6, 3655-3662).

We pursue molecular mimetic approaches to proceed form plasmonic atoms and molecules to plasmonic polymers and supercrystals with tailored optical properties and directionality.

 

1) Plasmonic atoms and molecules:

When gold atoms start to agglomerate into clusters consisting of at least 200 units, a new, freeelectron system emerges, in which conduction electrons collectively oscillate in the presence of electromagnetic radiation giving rise to LSPRs (Localized Surface Plasmon Resonances). This new entity -the plasmonic particle- can interact with electromagnetic radiations in a similar way to atoms, but optical phenomena (absorption, emission, or scattering) emerge in the visible spectral range (<2.6 eV) rather than the UV (Anales de Química 2011, 17, 221-228).

We are interested in important related concepts about the interaction of light with molecules and plasmonic nanoparticles and their plasmonic applications (J. Phys. Chem. Lett. 2011, 2, 2466-2471):

 

2) Plasmonic Polymers:

Plasmonic polymers can be considered as large nanostructures, built up by repetition of smaller nanosized units -metal nanoparticles- mimicking the structures of 1D and 2D molecular polymers and even block copolymers. The bonding between the building blocks is of significant importance since covalent bonds lead to essentially irreversible linkage of the metal nanocrystals, whereas noncovalent interactions may allow potentially reversible dynamic binding (Angew. Chem. Int. Ed. 2011, 50, 5499-5503).

Aiming at mimicking biomolecular polymers with increased dimensionality, our recent efforts have led to the design of nanomaterials with controlled 3D chiral structures and morphologies. We have illustrated the promising potential of these chiral metallic nanostructures, which exploit the characteristic LSPR of metal colloids to produce intense optical activities due to significant differences in extinction between left and right circularly polarized light (Nano Today 2011, 6, 381-400).

 

3) Plasmonic Supercrystals:

The idea that molecules self-assemble in different fashions as they change from the disordered isotropic liquid state to the rigorously 3D-ordered crystalline phase, passing through intermediate liquid crystalline phases has been explored in the field of plasmonic crystals as well.

We have shown that anisotropic nanocrystal superstructures can result from the formation of nematic and smectic liquid crystalline phases upon solvent evaporation, in which plasmonic nanoparticles are oriented
in layers with close-packed hexagonal arrangement due to the self-assembly of amphiphilic capping molecules (Angew. Chem. Int. Ed. 2009, 48 , 9484-9488).

 

Moreover, the fabrication of supercrystals of standing core-shell gold-silver nanorods stabilized by gemini surfactants provides SERS substrates with high optical activity, large homogenous sensing areas and the potential to maximize the SERS signal with respect to their gold nanorod supercrystal counterparts (Adv. Opt. Mater. 2013, 1, 477-481).

Additionally, using supramolecular approaches, once formed, the self-assembled supercrystals can be fully redispersed in water. The reversibility of the crystallization process may offer an excellent reusable material to prepare gold nanoparticle inks and optical sensors with the potential to be recovered after use (Angew. Chem. Int. Ed. 2014, DOI: 10.1002/anie.201406323).

Equipment of the Nano Chemistry Group:

UVICON XL spectrophotometer (Bio-Tex Instruments)

 

AMINCO Bowman Series 2 spectrofluorimeter

 

FL-900 spectrofluorimeter Edinburgh Analytical Instruments

 

EasyLife Lifetime Spectrometer

 

Densitometer and Speed of Sound Equipment

 

Laboratory facilities

 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

 

 

Physical Chemistry Department I
Faculty of Chemistry

Universidad Complutense de Madrid
Avda. Complutense s/n, 28040 - Madrid (Spain)

Aulario y Biblioteca