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C. Copper Polymers Assembled by Aliphatic Dithioether and Polythioether Ligands

C. Copper Polymers Assembled by Aliphatic Dithioether and Polythioether Ligands

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Luminescent Copper Polymers Assembled by Thioether Ligands



135



FIGURE 46. View of the 1D ribbon of [(CuI)2{μ-CyS(CH2)4SCy}2]n 32 incorporating

dinuclear Cu(μ-I2)Cu motifs along the a axis.



[(CuI)2{μ-CyS(CH2)4SCy}2]n 32. X-ray diffraction analysis confirmed inded that

replacement of -SPh by -SCy has a marked effect on the topology and nuclearity

compared to the PhS(CH2)4SPh-linked 2D polymer 16.

The overall topology of compound 31 is related to that of [(CuI)2{μ-PhS

(CH2)5SPh}2]n 22, the infinite double-stranded ribbon consisting of Cu(μ2-I)2

dimers, which are interconnected with the adjacent inorganic rhomboids through

bridging dithioether ligands (Fig. 46). A striking difference, however, concerns the

extreme long Cu?Cu separation, which exceeds even that reported for

[Cu2I2(dtpcp)2] Á thf (dtpcp 5 2,11 dithia[3.3]paracyclophane) [3.24 vs. 3.18 A˚].150

With the objective to study the impact of the substitution pattern of a

series of bis(cyclohexylthiomethyl)benzene ligands on the network topologies,

Kim’s group synthesized the 1,2-(L33), 1,3-(L34), and 1,4-bis(cyclohexylthiomethyl)benzene (L35) isomers and reacted them with CuI in MeCN

solution according Scheme 15.155 Whereas the reaction of the ortho-isomer L33

afforded the dinuclear complex 33 (d Cu?Cu 2.9560(5) A˚), reaction of CuI

with the meta-isomer L34 produced the 2D polymer 34, incorporating rhomboid Cu(μ-I)2Cu units with CuÀCu separations of 2.7566(9) A˚. In the case of

the para-isomer L35, the 1D polymer 35 was isolated, in which cubane-like

Cu4I4 clusters are located at the nodes of a loop-chain framework (Fig. 47).

In contrast to compounds 33 and 34, the 1D polymer 35 exhibits a bright

green emission at about 521 nm after excitation at 323 nm (Fig. 48). The

position of λmax is explained by the relatively high energy level of the LUMO

and a bonding character owing to somewhat longer CuÀCu distances in the

range of 2.7719À2.8568 A˚ compared to other thioether and pyridine ligated

cubane clusters with mean distances ,2.8 A˚.

The π-conjugated aromatic tetrakisthioether ligand 9,10-bis{[3,4-bis

(methylthio)phenyl]ethynyl]}anthracene L36 interacts with CuCN to form a

2D hybride network of composition L36 Á 2 CuCN, according Scheme 16.156



136



Luminescent Oligomeric and Polymeric Copper Coordination



S



S

S



S

I



L33



Cu



Cu

I



MeCN



S



S



Dinuclear 33



S



S



Cu

S



L34

CuI



Cu



I

I



S



I



Cu



I



S



S



Cu



Cu



I



Cu



I



MeCN



S



S

Cu



S



I



S



Cu



I



2D brick-wall polymer 34



S



S



S



L35

MeCN



I

Cu



S



Cu



I



Cu

I



I



I



Cu



Cu



S



Cu

Cu

I



I



I



Cu



S



1D loop chain polymer 35



SCHEME 15



FIGURE 47. View of the 1D chain of [Cu4I4{μ-L35}2]n 35. H atoms are omitted for

clarity.



Figure 49 shows that CuCN forms cyanide-bridged CuÀCNÀCu zigzag chains

as inorganic submotifs, which are linked by the L35 ligands through

thioetherÀCu bonds with CuÀS distances of 2.537(8) and 2.6553 (8) A˚,

resulting in a distorted honeycomb net along the bc plane. The L36 ligands,



Luminescent Copper Polymers Assembled by Thioether Ligands



137



Excitation

Emission



300



Intensity (a.u.)



250

200

150

100

50

0

300



350



400



450

500

Wavelength (nm)



550



600



FIGURE 48. Solid-state excitation (dashed line) and emission spectra (solid line) of 35,

recorded at ambient temperature. (Modified from Ref. 155.)



FIGURE 49. View of the b,c plane of the 2D network of 36, showing the CuÀCNÀCu

chains.



138



Luminescent Oligomeric and Polymeric Copper Coordination



S

S ϩ CuCN



S



90 ЊC

55 %



S



L36 · 2 CuCN

2D polymer 36



L36



SCHEME 16



with an almost planar conformation, are organized into columns that are

parallel and alternate with the CuCN chains within the honeycomb sheet.

The thioether ligand L36 and CuCN in their separate solid-state forms

feature emissions at 549 and 400 nm, respectively. The most intense emission of

polymer 36 is observed red shifted at 614 nm, which is ascribed to the different

packing of the L36 linkers as well as the electronic interaction of across the L36

unsaturated molecules and the CuÀCNÀCu chains.



D. Copper Polymers Assembled by Dithioether

and Polythioether Ligands Bearing Heteroelements

in the Spacer Unit

Several metal-organic polymers assembled by dithioether ligands, which

are functionalized by heteroelements such as O, N, or Si in the spacer unit,

have been recently described and reacted with Cu(I) salts. For example, the 2D

square-grid coordination polymer 37 incorporating the 16-membered dithiaoxa

crown-ether L37 has been prepared by a self-assembly process involving the

interaction of the dithiaoxa macrocycle with CuCN (Scheme 17); the parallel

reaction of the dithiaoxa crown-ether with CuI afforded the 1D doublestranded coordination polymer 37’. This example demonstrates, how the nature of the counterion can control the form of the network.157

When using the 18-membered thioxa-macrocycle L38 as the assembling

ligand for the construction of networks containing CuI-based connecting

nodes, a mixture of coordination polymers was obtained (Scheme 18).158

Crystallographically characterized 2D polymer [Cu2I2(L38)2] 38, which is

nonemissive, consists of dinuclear Cu(μ2-I)2Cu units with loose nonbonding

Cu?Cu contacts. Each rhomboid core is bonded to four L38 macrocycles via

CuÀS bonds. The second compound, with composition [Cu4I4(L38)2] 38u, was

separated manually from 38. In the solid state at ambient temperature, product

38u exhibits a broad unstructured emission at B570 nm after excitation at 360

nm; a cluster-centered excited state with mixed halide to metal charge transfer

is thought to be origin of this band.

The same group has also investigated the reactivity of the related ligand

calix[4]bis(thiacrown-5) L39 (Fig. 48) with alternating conformation toward

AgPF6 and CuI.159 In the latter case, two 3D polymers with different topologies co-crystallized from an acetonitrile solution. The monoclinic crystals 39



Luminescent Copper Polymers Assembled by Thioether Ligands



C



O



C



O



N

CuCN



O



139



C



O



N



Cu



S



S



O



N



Cu



C



S



S



O



Cu



C



C

O



O



O



O



N



N

Cu



S



S



O



N



Cu



S



S



O



Cu



Square-grid-type 2D polymer 37

O



O

Double-stranded 1D polymer 37'



S



O



S

O



O



O



O



L37

S



S



O



S



CuI



I



I



I

Cu



S



O



Cu



Cu



Cu

I



I

Cu



O



S



O



S



I

Cu



O



S



O



O



S



O



SCHEME 17



O



O



CuI



S



S



MeCN/CH2Cl2



[Cu2I2(L38)2] ϩ [Cu4I4(L38)2]'

2D polymer 38



polymer 38'



nonemissive



emissive



L38

SCHEME 18



consist of 3D networks, in which Cu(μ2I)2Cu rhomboids with short Cu?Cu

distances of 2.654(7) A˚ coordinate the functionalized calixarene ligands in an

exocyclic manner. In the orthorhombic crystals, the 3D networks of composition [Cu4I4(L39)] 39u are assembled through closed cubane-like Cu4I4 clusters,

which act as three-dimensional connecting nodes bound to four different tetrakisthioether ligands. The individual Cu?Cu distances within the cubes are

variable and range from 2.607 to 2.995 A˚, the mean value being 2.77 A˚ (at 173 K).



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C. Copper Polymers Assembled by Aliphatic Dithioether and Polythioether Ligands

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