1 Introduction
Devices of the future that are able to efficiently transfer and manipulate light energy
at the molecular level are inspired by nature, namely, by the processes taking place in
photosynthetic systems. In green plants, part of the visible (vis) light (blue and red
spectral regions) is absorbed by chlorophyll pigments. The chromophore units in the
pigments include hundreds of specifically arranged porphyrin molecules that play
the role of molecular antennas organized in order to efficiently absorb light. Their
spatial orientation allows a highly efficient transfer of the excitation energy to nearby
chromophores that reach the reaction center, where the energy can be further utilized
for biochemical processes. The chromophoric units are arranged in a protein skeleton
to prevent the formation of molecular aggregates that would significantly inhibit the
photoactivity and thus reduce energy transfer efficiency. Knowledge about these
natural systems can also be applied in strategies and designs of artificial hybrid
materials capable of conducting the controlled energy transfer process. Such materials based on zeolites and organic dyes have been extensively investigated [1–3].
In addition to the controlled utilization of light energy, Förster resonance energy
transfer (FRET) itself is significant in countless areas of modern industries and in a
variety of applications and fields of scientific research. One promising type of system
for controlled FRET is hybrid materials. The hosts provide the opportunity to control
the separation distance between the interacting molecules and suppress the molecular aggregation. In the hybrid materials, the luminophores could be sufficiently
stabilized and protected, especially from atmospheric oxygen and moisture. It is
possible to prepare a wide variety of materials with different optical properties
merely by combining different ratios of layered hosts, dyes, and other constituents
of the materials. Such an approach has potential for the development of new types of
devices such as hybrid light-emitting devices, diodes, sensors, white light-emitting
systems, etc. The combination of proper dyes and the control of energy transfer
processes can help to control the color of emitted light [3]. In some cases, the color
variants can be changed by external stimuli. Other phenomena partially related to
FRET are photostabilization, photosensitization, photocatalysis, and the
photocatalytic decomposition of various pollutants and agrochemicals, etc.
The materials of the future are those whose properties and functionality can be
changed by external stimuli. Examples of applications of such systems are chemical
sensors or probes. The FRET phenomenon can be used for the analysis of various
substances or for the measurements of some physical quantities. From the perspective of nanomaterial research, FRET can serve as a ruler for measuring distances at
the molecular level. To describe the dynamics of nanoparticle systems, FRET
anisotropy methods have been widely used in molecular biology and macromolecular chemistry. Many optical probes and sensors have important applications in
optical microscopy. Fluorescence imaging by optical microscopy is one of the most
effective techniques for the noninvasive monitoring of cells and biomolecules in real
time and in their natural environments. It is fairly accurate in terms of spatial
resolution, specific to target sites, and is a suitable tool for obtaining basic
Resonance Energy Transfer in Hybrid Systems of Photoactive Dye Molecules and. . .
207
Devices of the future that are able to efficiently transfer and manipulate light energy
at the molecular level are inspired by nature, namely, by the processes taking place in
photosynthetic systems. In green plants, part of the visible (vis) light (blue and red
spectral regions) is absorbed by chlorophyll pigments. The chromophore units in the
pigments include hundreds of specifically arranged porphyrin molecules that play
the role of molecular antennas organized in order to efficiently absorb light. Their
spatial orientation allows a highly efficient transfer of the excitation energy to nearby
chromophores that reach the reaction center, where the energy can be further utilized
for biochemical processes. The chromophoric units are arranged in a protein skeleton
to prevent the formation of molecular aggregates that would significantly inhibit the
photoactivity and thus reduce energy transfer efficiency. Knowledge about these
natural systems can also be applied in strategies and designs of artificial hybrid
materials capable of conducting the controlled energy transfer process. Such materials based on zeolites and organic dyes have been extensively investigated [1–3].
In addition to the controlled utilization of light energy, Förster resonance energy
transfer (FRET) itself is significant in countless areas of modern industries and in a
variety of applications and fields of scientific research. One promising type of system
for controlled FRET is hybrid materials. The hosts provide the opportunity to control
the separation distance between the interacting molecules and suppress the molecular aggregation. In the hybrid materials, the luminophores could be sufficiently
stabilized and protected, especially from atmospheric oxygen and moisture. It is
possible to prepare a wide variety of materials with different optical properties
merely by combining different ratios of layered hosts, dyes, and other constituents
of the materials. Such an approach has potential for the development of new types of
devices such as hybrid light-emitting devices, diodes, sensors, white light-emitting
systems, etc. The combination of proper dyes and the control of energy transfer
processes can help to control the color of emitted light [3]. In some cases, the color
variants can be changed by external stimuli. Other phenomena partially related to
FRET are photostabilization, photosensitization, photocatalysis, and the
photocatalytic decomposition of various pollutants and agrochemicals, etc.
The materials of the future are those whose properties and functionality can be
changed by external stimuli. Examples of applications of such systems are chemical
sensors or probes. The FRET phenomenon can be used for the analysis of various
substances or for the measurements of some physical quantities. From the perspective of nanomaterial research, FRET can serve as a ruler for measuring distances at
the molecular level. To describe the dynamics of nanoparticle systems, FRET
anisotropy methods have been widely used in molecular biology and macromolecular chemistry. Many optical probes and sensors have important applications in
optical microscopy. Fluorescence imaging by optical microscopy is one of the most
effective techniques for the noninvasive monitoring of cells and biomolecules in real
time and in their natural environments. It is fairly accurate in terms of spatial
resolution, specific to target sites, and is a suitable tool for obtaining basic
Resonance Energy Transfer in Hybrid Systems of Photoactive Dye Molecules and. . .
207