Adding Color to Green Chemistry? An Overview of the Fundamentals and Potential of Chlorophylls

Photochemical Transformations Involving Porphyrins and Phthalocyanines

“…However, this situation is rapidly changing with the renewed interest in solar energy conversion systems. An overview of the various synthetic and structural principles to model the components of the photosynthetic apparatus has been given in the relevant chapter on zinc(II) porphyrins (Senge and Sergeeva 2006). <Figure 3> 3.1 Chlorophylls and Related Pigments Chlorophylls (chl) and bacteriochlorophylls (bchl) are the ubiquitous pigments of photosynthetic organisms and the predominant class of magnesium tetrapyrroles in nature.…”

“…Chl a and b can be obtained easily from plants or algae and their synthetic chemistry has mainly targeted total syntheses and medicinal application in photodynamic therapy (PDT) (Scheer 1991, Senge 1992. <Chemical Structure 2> However, many other similar photosynthetic pigments occur in nature (Scheer 1991, Senge 1992, Sergeeva and Senge 2008, Senge and Richter 2006. All share either a phytochlorin 7 or a 7,8-dihydrophytochlorin framework and more than one hundred related pigments have been isolated .)…”

“…Both the photoinduced electron transfer and recombination of the charge-separated state depended on the number and position of the porphyrin units attached to phthalocyanines (Bian et al 2007). Many systems were prepared and detailed photophysical analyses were carried out for zinc tetrapyrrole systems (Senge and Sergeeva 2006). Other examples for hybrid systems are slippedcofacial dimers consisting of directly linked zinc porphyrin -zinc phthalocyanine units (Ito et al 2006).…”

Chlorophylls: A Personal Snapshot

“…Besides their involvement in primary charge separation in the reaction center, they serve as light-harvesting and light-sensing pigments, they also have additional functions, e.g., in inter-system electron transfer. Chls also have a wealth of applications [ 5 , 6 ]: in basic science, modified pigments allow for functional analyses; in medicine, they serve as photosensitizers. Chl derivatives are used as colorants for food and cosmetics, they are also candidates for optoelectronic use.…”