Ball-type Pcs

Research reporting on the synthesis and properties of ball-type Pcs with the number of different cross links is rather rare in the literature. 

Currently, two methods have been followed for the synthesis of ball-type Pcs synthesis in solvent and in the solid phase. 

The first published ball-type Pc was obtained by the reaction of l,2-bis(3,4-dicyanophcnoxymclhylj-benzenc with zinc acetate and DBU as base in boiling dichlorobenzene under argon atmosphere for 14 h. The yield of this reaction was rather low (1.84%) [35], In the next study, the same ball-type ZnPc was prepared by the solid-phase method increasing the amount of zinc acetate by a factor of 10 and heating the reaction mixture in the absence of catalysts at 250°C for 5 min. This time, the yield was 33% [36],... 

Because of expected electrical, electrochemical, optical, chemo-sensor, and other properties of the ball-type Pcs, several metallo and metal-free ball-type Pcs with different linkers have been reported. Metallo and metal free ball-type Pcs containing four calyx[4]arene units as linkers have been synthesized, Fig. 1 [37], The structures of compounds 1-3 were confirmed by UV-vis, IR, 1II-NMR, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and elemental analysis. Because of their unique structure and versatile complexation properties [38], calixarenes were found to be one type of interesting compounds to be incorporated into Pc. The cone conformation of the t-butylcalix[4]arene direct... 

Starting with l,l/-methylene-di(2-naphtol) 13 and 5-nitro-phthalonitrile 12, bis-phthalonitrile 14 was prepared. To obtain metal-free ball-type Pc 15, a suspension of 14 in dry amyl alcohol and lithium metal was heated in a sealed tube at 170°C for 8 h, Fig. 4. The metallo Pcs with zinc 16 and cobalt 17 were synthesized by heating a... 

But, the reaction of 14 with the cobalt salt in a solid phase at 320°C for 10 min and washing the reaction mixture with hot methanol and acetic acid gave a mixture of several Pcs. MALDI-TOF measurements with the matrix of 2,5-dihydroxybenzoic acid showed that not only ball-type Pc 17 but also four more Pcs 18,19, 20, and 21 were present in the product, Figs. 5 and 6 [43], Two of these five Pcs, namely 17 and 18 in Fig. 5, could be separated with silica gel column, but three other Pcs, namely 19,20, and 21, could not be isolated. 

Fig. 9. After removing the mono acetal groups of 33 and 34 by hydrogenation, ball-type Pcs with free hydroxy groups 35 and 36 or water-soluble alkali metal salts of ball-type Pcs 37 and 38 were obtained.

Those free eight hydroxy groups of the ball-type Pcs give the possibility to make further reactions to obtain novel ball-type Pcs with various properties. For example, the eight hydroxy groups can be converted to four crown-ethers 39, 40, 39a, and 40a (Fig. 10) [47] or to eight perfluorodecyl units 42 and 43 (Fig. 11) [48],... 

Isopropylidendioxydiphenyl was used as a bridged compound in order to obtain ball-type Pc. Mixing the bisphthalonitril derivative 44 with zinc or cobalt salt in the solid phase and heating the mixtures in a sealed tube at 250° C for 10 min gave the Pcs 45 and 46 with the yields of 9.39 and 8.27%, respectively, Fig. 12 [49],... 

Not all reactions in the solid phase convert bisphthalonitrile derivatives into ball-type Pcs. One example of such reactions is the conversion of the bisphthalonitrile derivative of phenolphthalein into ball-type Pc [50], As can be seen in Fig. 13, when a solid mixture of bisphthalonitrile 48 and metal salt was heated in a sealed tube at 320° C for 5 min, only mono Pcs 49 and 50 were formed. Further reaction of 49 or 50 with an excess of the corresponding metal salt in a refluxing solvent for 24 h resulted in the formation of ball-type Pcs 51 or 52. 

The UV-vis spectra of the ball-type Pcs resemble those of the other Pcs with some differences. Depending on the bridged compounds, metals, and solvent, the electronic and other properties of ball-type Pcs change dramatically. Also, due to the bridged substituents, the distance between two Pc molecules of the ball-type Pcs changes considerably, affecting their degree of interaction. 

The electronic spectra of Lu(III) 10 and In(III) 11 complexes of calix[4]arene ball-type Pcs in Fig. 3 are worthy of being cited, Fig. 15. It can be seen from the electronic absorption spectrum of 10 that Q band splits into two, with maxima 708 and 673 nm, as a result of exciton coupling between two Pc units. Coumpond 11 exhibits a broadened Q band indicating additional amount of aggregation of that compound, and a weak band around 630 nm due to exciton coupling [42,52-57]. 

The electronic spectra of the other published ball-type Pcs resemble more or less to each other with respect to the current factors of the theory [24,41,44,46,49,50]. 

The electrochemical and spectroelectrochemical properties of some ball-type Pcs have been investigated and compared with those of the monomer or clamshell dimeric Pcs which contain the same substituents at the periphery as bridged groups. The striking feature of cyclic voltammetric (CV) measurements of the ball-type Pcs is the shift of potential due to HOMO-HOMO interactions between the cofacial Pc rings [38]. For example, the voltammetric measurements of the four... 

MALDI-TOF mass measurement of the ball-type Pcs is the most powerful technique in order to determine their molecular weight and to characterize their structures. In this technique, it is important to find the appropriate matrix in order to obtain highly resolved spectra, thereby obtaining good mass resolution. If we take into account the MALDI-TOF-MS of the ball-type Pcs 33, 34, 35, and 36 in Fig. 9 [46] and 39 and 40 in Fig. 10 [47] as examples, the protonated molecular ion peaks of 33 and 34 were observed at low intensity, but the sodium adduct peaks of Pcs 33 and 34 were found to be dominant, intense peaks in the linear-mode MALDI-TOF-MS by using... 

MALDI-TOF-MS of the same ball-type Pc substituted with four 6-crown-5-ether units 39 and 40 in Fig. 10 [47] showed that not only the right mass but also the pure compounds were present, Figs. 22, 23. 

Positive-ion and reflectron-mode MALDI spectra of the CoPc 40 could be obtained in ACCA matrix. The isotopic peak distribution of the protonated molecular ion peak was due to the carbon and cobalt isotopes, and the experimental isotopic peak distribution (shown as inset) in Fig. 23 corresponded to the theoretical calculations. For the other ball-type Pcs, MALDI-TOF-MS and their details can be found in the following references or in the Supplementary Materials sections [24,25,41,42,44,45,49],... 

In case of ball-type Pcs, there are only two studies reported on the NLO and OL properties of metallo and double-decker Lu(III) and In(III) Pcs in the literature [42, 60]. The NL refraction and absorption dependence on thermal effect for 4-ns pulse duration in ball-type with four t-butylcalix[4]arene bridged ZnPc 2 in Fig. 1 in solution have been studied [60]. z-Scan experiments were performed on 2 in chloroform solution with a 10-cm-focal length lens. The results are shown in Fig. 24a. 

We summarized in this chapter ball-type Pcs, which are a new class of Pcs first published 6 years ago [35]. Since that time, several papers appeared in the literature, which were published only by our group as far as we know. Therefore, comparison... 

---