Dr. George Pistolis, Research Director
NCSR “Demokritos”

15310 Aghia Paraskevi, Attiki, Greece
Tel: +30 210 6503637
e-mail: g.pistolis"at"inn.demokritos.gr

Dr. George Pistolis leads a multidisciplinary research program devoted to the Molecular Engineering of Photo-functional Self-Assembled Nanosystems. More specifically his research focuses on the design, synthesis, characterization and in-depth spectroscopy of functional dyes and their programmable self-assembly into well-defined photo-(re)active nanoarchitectures with tailored properties for potential applications in lighting, solar energy conversion, electronics – photonics, molecular sensing and machinery.

Over the past decade and more, our group has been extensively studying various aspects of supramolecular architectures - spanning from simple inclusion compounds to complex self –assembled nanostructures - such as,
• Guest stability and Dynamics in Nanocavities
• Stereoselective host-guest interactions
• Structure, stability and dynamics of non-covalently bonded nanotubes and supramolecular polymers based mainly on cyclodextrins
• Excited-state kinetics and thermodynamics of reversible isomerizations that can lead to autonomous mechanical response at the molecular level
• Fluorescent sensors for the signaling of molecular and macromolecular recognition events
• Structural features and control release properties of self-assembled nanosystems with fluorescent “on-off” switches
• Photophysics, dynamics and energy transfer phenomena in blue-emitting linear and dendronized photonic polymers
• Color tunability engineering in Organic Light Emitting Diodes and Optical Lithography

After having obtained a sufficient expertise on the aforementioned thematic areas, the new activities of our group focus on the design, supramolecular synthesis, characterization and comprehensive spectroscopy of cleverly engineered self-assembled complex nanoarchitectures capable of exploiting light for tuning and tailoring the properties of advanced materials. More specifically, we are interested in constructing intensely absorbing/emitting metallosupramolecular host nanoarchitectures with size-adjustable nanoporous cavities capable of accommodating a large variety of semiconducting materials. We further intend to achieve precise control over the spatial topology and the energy levels of the interacting dipoles in the above multichromophoric arrays and to provide new insights into beneficial pathways for harvesting, transferring, (up)-converting and funnelling electronic energy in the condensed phase for multifunctional applications including, accumulation and tuning in photo(electro)-luminescence, light-harvesting and solar energy conversion, organic electronics and photovoltaics, photomechanical responses and molecular sensing.

The main methodologies and techniques involved in our research comprise:
• Design and synthesis of photomolecular building blocks and their subsequent directed supramolecular synthesis – via combinations of selected self-assembly protocols - into well-defined photo-functional nanoarchitectures. Verification of the structures is made by means of structural (multinuclear NMR & 2D NMR, ESI-MS, X-ray crystallography, SAXS, STM, AFM) and electronic/optical (UV/Vis/NIR absorption and fluorescence) characterization techniques.
• Electronic spectroscopy methods, both steady-state and time-resolved, to study photophysical and photochemical processes, such as kinetics and thermodynamics of energy/electron transfer phenomena – photomechanical conversions, rotational dynamics etc. We perform research on subnanosecond to millisecond time scales in NCSR Demokritos. Ultrafast measurements (femto-to-picoseconds) are investigated in collaboration with Dept. of Physics, University of Patras and with laboratories in Europe.

 

Selected Publications

• N. Karakostas, I. M. Mavridis, K. Seintis, M. Fakis, E. N. Koini, I. D. Petsalakis, G. Pistolis
“Highly efficient and unidirectional energy transfer within a tightly self-assembled host–guest multichromophoric array”
Chem. Comm., 2013, DOI: 10.1039/C3CC48076C

• Kaloudi-Chantzea, N. Karakostas, F. Pitterl, C. P. Raptopoulou, N. Glezos, G. Pistolis “Efficient supramolecular synthesis of a robust circular light-harvesting Bodipy-dye based array”
Chem. Comm., 2012, 48, 12213–12215 pdf

• I. Balomenou, A. Kaloudi-Chantzea, N. Karakostas, K. Yannakopoulou, I. M. Mavridis and G. Pistolis “Controlled Stereospecificity of a Volume-Conserving Adiabatic Photoisomerization within a Nanotubular Self-Assembled Cage: Insights Into Machinery Behavior ”
J. Phys. Chem 2011, 115, 10665-10681 pdf

• Kaloudi-Chantzea A, Karakostas N,. Raptopoulou C. P, Psycharis V, Saridakis E, Griebel J, Hermann R, Pistolis G
“Coordination-Driven Self Assembly of a Brilliantly Fluorescent Rhomboid Cavitand Composed of Bodipy-Dye Subunits”
J. Am. Chem. Soc., 2010, 132 , 16327-16329 pdf
For a highlight see '" Unquenched Fluorescent Metal Nanocages"T M Swager and D.B. Walker, Synfacts, 2, 0151 (2011)

• Balomenou I, Kaloudi-Chantzea A, Bokias G,. Kallitsis J. K, Raptopoulou C. P, Terzis A, and Pistolis G “Medium Effect on the Geometric Isomerism of a Centrosymmetrically Disubstituted Naphthalene Derivative with Flexible Methoxytriethylene Glycol Chains”
J. Phys. Chem.B , 2010, 114, 8181-8190 pdf

• I. Balomenou and G. Pistolis
“Pure Isolation and Stabilization of Energetically highly Disfavored Geometric Isomers by Controlling the Stereoselectivity of Supramolecular Interactions in Tailored Host-Guest Systems”
J. Phys. Chem.B, 2010, 114, 780-785 pdf

• I. Balomenou and G. Pistolis
“Torsional Photoisomerization Proceeding Adiabatically Through a Volume-Conserving Pathway in Uninhibited Fluid Media”
Chem. Eur. J., 2009, 15, 4228-4232 pdf

• I. Balomenou and G. Pistolis
“Experimental evidence for a highly reversible excited state equilibrium between s-cis and s-trans rotational isomers of 2-methoxynaphthalene in solution”
J. Am. Chem. Soc. 2007, 129, 13247-13253 pdf

• M. Vasilopoulou, G. Pistolis, D. Georgiadou and P. Argitis
“Tuning the emitting colour of OLEDs through photochemical transformation: Towards single-layer three color generation”
Adv. Funct. Mat. 2007, 17, 3477-3485 pdf

• V. Vergadou, G. Pistolis , A. Michaelides, G. Varvounis, M. Siskos N. Boukos and S. Skoulika
“Self-organization of four symmetric tri-phenyl-benzene derivatives”
Crystal Growth & Design, 2006, 6, 2486-2492 pdf

• G. Pistolis and I. Balomenou
“Cyclodextrin Cavity Size Effect On the Complexation and Rotational Dynamics of the Laser dye 2,5- Diphenyl-1, 3,4-oxadiazole: From Singly-Occupied Complexes to their Nanotubular Self-Assemblies”
J. Phys. Chem. B, 2006, 110, 16428-16438 pdf

• G. Pistolis, A. K. Andreopoulou, A. Malliaris, and J. K. Kallitsis
“Direct observation of odd-even effect in dilute polymeric solutions: A time-resolved fluorescence anisotropy study”
J. Phys. Chem. B, 2005, 109, 11538-11543 pdf

• G. Pistolis, A. K. Andreopoulou, A. Malliaris, and J. K. Kallitsis
“Effect of the Chain Length on the Photonic Efficiency of Aromatic-Aliphatic Dendronized Polyethers”
Macromolecules, 2004, 37, 1524-1530 pdf

• G. Pistolis and A. Malliaris
“Evidence for Highly Selective Supramolecular Formation between Perylene/γ -CD and Pyrene/ γ-CD Complexes in Water
J. Phys. Chem. B, 2004, 108, 2846-2850 pdf