BODIPY dyes and their derivatives: syntheses and spectroscopic properties.

The world of organic luminophores has been confined for a long time to fairly standard biological labeling applications and to certain analytical tests. Recently, however, the field has undergone a major change of direction, driven by the dual needs to develop novel organic electronic materials and to fuel the rapidly emerging nanotechnologies. Among the many diverse fluorescent molecules, the Bodipy family, first developed as luminescent tags and laser dyes, has become a cornerstone for these new applications. The near future looks extremely bright for "porphyrin's little sister".

The Chemistry of Fluorescent Bodipy Dyes: Versatility Unsurpassed

3.7. Palladium Nanoparticles as Catalysts 888 3.8. Other Transition-Metal Complexes 888 3.9. Transition-Metal-Free Reactions 889 4. Applications 889 4.1. Alkynylation of Arenes 889 4.2. Alkynylation of Heterocycles 891 4.3. Synthesis of Enynes and Enediynes 894 4.4. Synthesis of Ynones 896 4.5. Synthesis of Carbocyclic Systems 897 4.6. Synthesis of Heterocyclic Systems 898 4.7. Synthesis of Natural Products 903 4.8. Synthesis of Electronic and Electrooptical Molecules 906

https://www.chem.ccu.edu.tw/~joyce/referance/ericyang/Chem.%20Rev/Chem.%20Rev.%202007,%20107,%20874-922.pdf

The Sonogashira Reaction: A Booming Methodology in Synthetic Organic Chemistry†

The current state of understanding of molecular resonance energy transfer (RET) and recent developments in the field are reviewed. The development of more general theoretical approaches has uncovered some new principles underlying RET processes. This review brings many of these important new concepts together into a generalization of Forster's original theory. The conclusions of studies investigating the various approximations in Forster theory are summarized. Areas of present and future activity are discussed. The review covers Forster theory for donor-acceptor pairs and electronic coupling for singlet-singlet, triplet-triplet, and superexchange-mediated energy transfer. This includes the transition density picture of Coulombic coupling as well as electronic coupling between molecular aggregates (excitons). Spectral overlaps and ensemble energy transfer rates in disordered aggregates, the role of dielectric properties of the medium, weak versus strong coupling, and new models for energy transfer in complex molecular assemblies are also described.

/pdf/long-range-resonance-energy-transfer-in-molecular-systems-2t0z5zlmj8.pdf

Long-Range Resonance Energy Transfer in Molecular Systems

This review focuses on classifying different types of long wavelength absorbing BODIPY dyes based on the wide range of structural modification methods that have been adopted, and on tabulating their spectral and photophysical properties. The structure–property relationships are analyzed in depth with reference to molecular modeling calculations, so that the effectiveness of the different structural modification strategies for shifting the main BODIPY spectral bands to longer wavelengths can be readily compared, along with their effects on the fluorescence quantum yield (ΦF) values. This should facilitate the future rational design of red/NIR region BODIPY dyes for a wide range of different applications.

Structural modification strategies for the rational design of red/NIR region BODIPYs

Light-harvesting arrays containing one, two, or eight boron-dipyrrin (BDPY) pigments and one porphyrin (free base or Zn chelate) have been synthesized using a modular building block approach. The reaction of pyrrole and 4-(BDPY)benzaldehyde or 3,5-bis(BDPY)benzaldehyde, prepared by Pd-mediated ethynylation with the corresponding iodo-benzaldehydes, affords the desired BDPY-porphyrin array in yields of 10−58%. The arrays are soluble in organic solvents and have been characterized by static and time-resolved absorption and fluorescence spectroscopy. The blue-green BDPY absorption complements spectral coverage of the porphyrin chromophores and rivals the intensity of the porphyrin Soret band when eight BDPY accessory pigments are present. Efficient energy transfer from the BDPY pigment(s) to the porphyrin (free base or Zn-chelate) is observed in arrays containing one or two (>90%) or eight (>85%) accessory pigments per porphyrin. Biphasic excited-state decay behavior is exhibited by the BDPY pigments in isol...

http://chembio.uconn.edu/Group_pubs/1995-1999/li_1998_jacs.pdf

Design, Synthesis, and Photodynamics of Light-Harvesting Arrays Comprised of a Porphyrin and One, Two, or Eight Boron-Dipyrrin Accessory Pigments

Synthesis of Ethyne-Linked or Butadiyne-Linked Porphyrin Arrays Using Mild, Copper-Free, Pd-Mediated Coupling Reactions

Beneficial effects of salts on an acid-catalyzed condensation leading to porphyrin formation

Zinc porphyrins have been widely used as surrogates for chlorophyll
(which contains magnesium) in photosynthetic model systems and molecular
photonic devices. In order to compare the photodynamic behaviour of Mg-
and Zn-porphyrins, dimeric and star-shaped pentameric arrays comprised of
free-base (Fb) and Mg- or Zn-porphyrins with intervening diarylethyne
linkers have been prepared. A modular building block approach is used to
couple ethynyl- or iodo-substituted porphyrins in defined metallation
states (Fb, Mg or Zn)via a Pd-catalysed reaction in 2–6 h.
The resulting arrays are purified in 45–80% overall yields by
combinations of size exclusion chromatography and adsorption
chromatography (≥95% purity). High solubility of the arrays in organic
solvents facilitates chemical and spectroscopic characterization. The
star-shaped Mg
 4
Fb- and Zn
 4
Fb-pentamers, where the
Fb-porphyrin is at the core of the array, have pairwise interactions
similar to those of dimeric MgFb- and ZnFb-arrays. The arrays have been
investigated by static and time-resolved absorption and fluorescence
spectroscopy, as well as resonance Raman spectroscopy. The major findings
include the following. (1) The rate of singlet excited-state energy
transfer from the Mg-porphyrin to the Fb-porphyrin [(31
ps)
 -1
 ] is comparable to that from the Zn-porphyrin to
the Fb-porphyrin [(26 ps)
 -1
 ] in the dimeric arrays.
Qualitatively similar results are obtained for the star-shaped pentamers.
The similar rates of energy transfer for the Mg- and Zn-containing arrays
are attributed to the fact that the electronic coupling between the
metalloporphyrin and Fb-porphyrin is approximately the same for Mg-
vs. Zn-containing arrays. (2) The quantum yield of energy
transfer is slightly higher in the Mg-arrays (99.7%) than in the Zn-arrays
(99.0%) due to the longer inherent lifetime of Mg-porphyrins (10 ns)
compared with Zn-porphyrins (2.5 ns). (3) The rate of energy transfer and
the magnitude of the electronic coupling are essentially independent of
the solvent polarity and the coordination geometry of the metalloporphyrin
(four- or five-coordinate for Zn-porphyrins, five- or six-coordinate for
Mg-porphyrins). (4) Polar solvents diminish the fluorescence yield and
lifetime of the excited Fb-porphyrin in arrays containing either Mg- or
Zn-porphyrins. These effects are attributed to charge-transfer quenching
of the Fb-porphyrin by the adjacent metalloporphyrin rather than to
changes in electronic coupling. The magnitude of the diminution is greater
for the Mg-containing arrays, which is due to the greater driving force
for charge separation. (5) The Zn-containing arrays are quite robust while
the Mg-containing arrays are slightly labile toward demetallation and
photooxidation. Taken together, these results indicate that
porphyrin-based nanostructures having high energy-transfer efficiencies
can be constructed from either Mg- or Zn-porphyrins. However,
Mg-containing arrays may be superior in situations where a succession of
energy-transfer steps occurs (due to a slightly higher yield per step) or
where charge transfer is a desirable feature. On the other hand,
Zn-porphyrins are better suited when it is desirable to avoid charge
transfer quenching reactions. Accordingly, the merits of constructing a
device from Mg- vs. Zn-containing porphyrins will be determined
by the interplay of all of the above
factors.

Feirong Li

Papers

Design, Synthesis, and Photodynamics of Light-Harvesting Arrays Comprised of a Porphyrin and One, Two, or Eight Boron-Dipyrrin Accessory Pigments

Synthesis of Ethyne-Linked or Butadiyne-Linked Porphyrin Arrays Using Mild, Copper-Free, Pd-Mediated Coupling Reactions

Beneficial effects of salts on an acid-catalyzed condensation leading to porphyrin formation

Effects of central metal ion (Mg, Zn) and solvent on singlet excited-state energy flow in porphyrin-based nanostructures

Synthetic Approaches to Regioisomerically Pure Porphyrins Bearing Four Different meso-Substituents.