Pyrrolyl Squaraines–Fifty Golden Years

Lynch, Daniel Ε.

doi:10.3390/met5031349

Cited by 22 publications

(13 citation statements)

References 106 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Condensation of N , N ‐disubstituted 2‐aminothiophenes 1 a – d with squaric acid leads to the formation of the desired thienosquaraines 2 a – d . The squaraine condensation reaction is known to be acid‐catalyzed by the squaric acid itself, which in most cases is strong enough to self‐catalyze its own reaction . This is an exceptional feature of SQ dyes compared with other class of optoelectronic materials, especially organic semiconductor materials, which are often prepared by metal‐catalyzed reactions.…”

Section: Resultsmentioning

confidence: 99%

Electro‐optical Properties of Neutral and Radical Ion Thienosquaraines

Maltese

Cospito

Beneduci

et al. 2016

Chemistry A European J

View full text Add to dashboard Cite

Thienosquaraines are an interesting class of electroactive dyes that are useful for applications in organic electronics. Herein, the redox chemistry and electrochromic response of a few newly synthesized thienosquaraines are presented. These properties are compared to those of the commercial 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl]squaraine. The stability of the radical ions formed in electrochemical processes strongly affects these properties, as shown by cyclic voltammetry, in situ spectroelectrochemistry, and quantum chemical calculations. Furthermore, all of the dyes show aggregation tendency resulting in panchromatic absorption covering the whole UV/Vis spectral range.

show abstract

Section: Resultsmentioning

confidence: 99%

Electro‐optical Properties of Neutral and Radical Ion Thienosquaraines

Maltese

Cospito

Beneduci

et al. 2016

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…Since that time these pyrrolyl squaraines have generated interesting compounds, having both optical and electrical conduction properties in addition to magnetic properties [116]. The synthesis of pyrrolyl squaraines occurs between the condensation of a pyrrole (or linked bispyrrole) and squaric acid ( Figure 27).…”

Section: Figure 26 Squaryl Metaphors Of Thiolketones and Ncyanoguanimentioning

confidence: 99%

Squaryl Molecular Metaphors – Application to Rational Drug Design and Imaging Agents

Kitson¹

2017

J Diagn Imaging Ther

View full text Add to dashboard Cite

Molecular Metaphors is the application of squaryl building blocks towards creative functional group chemistry to produce lead compounds and imaging agents. This strategy is applied to rational drug design and to various imaging agents that would normally contain conventional functional group chemistry. These, include carboxylic acids, α-amino acids, peptide bonds and phosphonates. Moreover, the squaryl metaphor is a precursor to complex organic molecules involving functional group interchange (FGI) and rearrangements. This article discusses the application of these metaphors in the area of neurochemistry, especially NMDA receptors. An important area of drug design is the inhibition of angiotensin II enzyme by the use of losartan. This commercial drug contains a tetrazole moiety that can be modified using the squaryl group to give a semisquarate derivative. These concepts can extend to the semisquarate of ibuprofen. Moreover, a discussion on peptidomimetics regarding the substitution of the peptide bond for squaramide allows for a change in the biological properties due to modification at the peptide bond. Furthermore, the topic on how squaryl metaphors can be exploited primarily by the central 1,3-hydroxyamide sequence to the generation of a novel class of HIV protease inhibitors. Also, squaryl metaphors can be used to develop potential inhibitors of glutathione and novel anti-migraine drugs. The discussion continues on the design of anticancer drugs: in particular, a novel class of metalloproteases, including phosphonates for semisquaramides, leading to squaryl nucleosides. This review concludes with the application of squaryl metaphors in the design of positron emission tomography (PET) and magnetic resonance imaging (MRI) agents towards theranostics. describe the ability of individual functional chemical groups to mimic other moieties [2,3]. KeywordsErlenmeyer rationalised these concepts and categorised isosteres into atoms, ions and molecules based on the valence level of electrons [4]. A further understanding by Friedman led to the term bioisosterism to include all atoms and molecules that fit the broadest definition of isosteres [5]. This approach was independent of whether the drug was an agonist or an antagonist towards biological activity.Moreover, Thornber applied the term bioisosterism to include subunits, groups or molecules that possess physicochemical properties of similar biological effects [6]. Finally, in 1991 Burger widened the definition of bioisosteres to include compounds or groups that possess similar molecular shapes and volumes independent of agonists or antagonists [7]. REVIEW ARTICLE Squaryl KitsonThese bioisosteres would require approximately the same distribution of electrons and give a high probability of generating comparable physical properties such as hydrophobicity [8]. Currently, bioisosterism is one of the most useful tools to the medicinal chemist in rational drug design and in particular regarding the carboxylic acid bioisosteres [9]. The carboxylic acid functional ...

show abstract

“…Pyrrolyl squaraines can further be subcategorized into 2‐yl and 3‐yl compounds (illustrated in Scheme ) with the definition arising from the positional contact from the pyrrole to the squarate core. The majority of pyrrolyl squaraines, including polysquaraines, thus far reported in both the scientific and patent literatures are pyrrol‐2‐yl‐derived symmetrical 1,3‐squarates . However, this microreview concentrates solely on the interesting facets of pyrrol‐3‐yl squaraine dye chemistry.…”

Section: Introductionmentioning

confidence: 99%

“…Squaraine dyes, compounds prepared via step‐wise condensation reactions of specific electron‐donating aromatic/heterocyclic ring systems and 3,4‐dihydroxycyclobut‐3‐ene‐1,2‐dione (squaric acid), have been extensively examined in both scientific and patent literatures since their first reported preparations in the late 1960s, with a number of review articles summarizing their many chemical/physical properties and applications . The vast majority of symmetrical squaraine dyes (where step‐wise condensation occurs in the same reaction pot) are represented by the six structural formulas in Scheme .…”

Section: Introductionmentioning

confidence: 99%

Microreview: Pyrrol‐3‐yl squaraines (including indol‐3‐yl squaraines)

Lynch

Hamilton

2018

Journal of Heterocyclic Chem

View full text Add to dashboard Cite

Pyrrol‐3‐yl squaraine dyes are prepared by the condensation of 3,4‐dihydroxycyclobut‐3‐ene‐1,2‐dione with two‐molar equivalence of a 2,5‐disubstituted pyrrole possessing a free β‐position, or substituted indoles with a similarly free β‐position. From the first reported syntheses of two indol‐3‐yl squaraines in 1966, numerous pyrrol‐3‐yl squaraines (including indol‐3‐yl squaraines) have been reported in both the scientific and patent literatures. This microreview highlights the synthesis, history, spectroscopy, and applications of pyrrol‐3‐yl squaraines from their first preparation to the present date.

show abstract

Pyrrolyl Squaraines–Fifty Golden Years

Cited by 22 publications

References 106 publications

Electro‐optical Properties of Neutral and Radical Ion Thienosquaraines

Electro‐optical Properties of Neutral and Radical Ion Thienosquaraines

Squaryl Molecular Metaphors – Application to Rational Drug Design and Imaging Agents

Microreview: Pyrrol‐3‐yl squaraines (including indol‐3‐yl squaraines)

Contact Info

Product

Resources

About