Carbolong Complexes as Photothermal Materials

Abstract

A series of photothermal cyclobutaosmapentalenes with conjugated groups attached to the metallacycle were synthesized from the reaction of OsCl 2 (PPh 3) 3 with an organic multiyne and PPh 3 , followed by a [2＋2] cycloaddition with terminal alkynes. These highly conjugated metallacycles showed broad UV-Vis absorption and good photothermal efficiency. These easily synthesized metallacycles represent a type of new photothermal material. Keywords organometallics; metallacycle; photothermal Metallacycles [1～5] containing a metal and a conjugated carbon-chain have attracted more and more attention as novel materials, because they could show both properties of the metal fragment and the organic framework. For instance, a series of planar Craig-type Möbius [6] metallacylces, called "carbolong" complexes, [6s～6t,7] have been reported. These "carbolong" complexes displayed various properties, including aggregation enhanced emission (AEE), [8] single-molecular conductivity, [9] photothermal conversion, [10] and photoacoustic response. [10a] Among these interesting properties, the photothermal conversion is one of the most important properties for carbolong complexes. For example, the photothermal efficiency of complex 1 (Figure 1a) is about equal to the performance of Au nanoparticles, [11] which are normally used for surface or physical modifications. [12] For comparison, complex 1 can be easily chemically modified and bonded to functional frameworks, obtaining functional macromolecules or micelles (Figure 1b). [10b～10d] Interestingly, the substituents in complex 1 have considerable influence on its absorption and photophysical properties. This effect has also been observed in complex 2 (Figure 1a), which shows a broad absorption covering the range of 700～900 nm owing to the J-aggregates in the substituent. [10c] Recently, our group discovered a simple way to prepare "carbolong" complexes in a one-pot reaction [13,14] by treatment of multiyne ("carbolong") with simple organometallic starting material. This one-pot "carbolong" method feasibly offered us a means of introducing more substituent groups into these matallacycles using different

Metallaaromatic Chemistry: History and Development

“…In consideration of the tremendous importance of aromatics in almost all fields of society, the prospect of metallaaromatics in material science should not be underrated. 533,541,[560][561][562][563]569,570 Of course, in order to promote their applications, more convenient synthetic routes are desirable.…”

“…Metallaaromatics possess different structures from traditional organic compounds, thus exhibiting diverse properties, and remarkably, their properties are easily adjusted by changing the ancillary ligands. In consideration of the tremendous importance of aromatics in almost all fields of society, the prospect of metallaaromatics in material science should not be underrated. ,,− ,, Of course, in order to promote their applications, more convenient synthetic routes are desirable.…”

Recent Advances in the Reactions of Cyclic Carbynes

“…The unique structure leads to novel properties. Novel metallacycles derived from the reactivity studies of metallapentalynes exhibited great application prospects in various areas, such as near-infrared dyes [47], photothermal therapy [74][75][76][77], phototherapy [78], and self-healing materials [79], enabling their potential applications in materials science and biomedicine. Future developments of metallabenzynes and metallapentalynes and exploration of their potential applications in catalysis [60], materials science and biomedicine would not only extend our perception of aromaticity in metallacycles, but also further enrich fundamental organometallic chemistry.…”

“…Furthermore, 18 O labeling experiments suggest that the oxygen atom in the furan ring comes from water [66]. With the synthetic methodology in hand, modifications were carried out to install olefinic groups in the metallapentalenofurans, which were then subjected to polymerization to provide metallapolymers exhibiting excellent stimuli-responsive properties [74,75]. The lactone-fused metallapentalynes 81 and 96 were formed if tetrafluoroboric acid was also present.…”

Acetylenic Carbon-Containing Stable Five-Membered Metallacycles

“…Except one example based on thorium (complex 13), five-membered metallacyclopentynes are restricted on group 4 metals; metallapentalynes have only been discovered for ruthenium and osmium complexes. Especially, in consideration that five-membered metallacycles are regarded as intermediates in many transition-metal catalyzed reactions, and the reactivity studies of metallapentalynes have given a variety of novel metallapentalene derivatives, which showed a great application prospect in various areas, such as near-infrared dyes [54], photothermal therapy [82][83][84], phototherapy [85], and self-healing materials [86], the chemistry on these two kinds of five-membered metallacycles is still far more than anticipated. Moreover, as special organometallic complexes, the application prospect of metallacycloalkynes and metallapentalynes in catalytic transformations should not be underestimated.…”