A. Ghorai et al. / Journal of Molecular Structure 1097 (2015) 52–60
53
Introduction
spectrometer respectively. X-ray powder patterns are collected
on a Philips PW-1710 automated diffractometer. Fluorescence
spectra were recorded on a Perkin Elmer LS55 Luminescence
Spectrometer. Voltammetry has been carried out in
Electrochemical Work Station of BAS, Epsilon model. The measure-
ments have been carried out at 293 K in dichloromethane solutions
Studies of copper(I) complexes with mixed ligand systems con-
taining triphenylphosphine and ligands having S and N donors,
have been increasing because of the flexibility of these ligands
and the different steric characteristics of the phosphine ligands,
which can modify the compound geometry [1]. The length of the
ligand moiety has also a great influence on the architectures of
the metal complexes [2].
À3
À4
containing 0.2 M TBAP as supporting 10 –10 M electrolyte.
Synthesis of ligand L1
The attention in the coordination chemistry of copper(I) deriva-
tives containing polydentate imino-pyridyl Schiff-base ligands is
rapidly growing because of their rich photophysical properties
1,8-Diaminooctane (0.145 g, 1 mmol) was dissolved in
anhydrous
methanol
(15 ml)
and
to
this
solution
[
3], intriguing structures [4], and varied application in metallo-
4-pyridinecarboxaldehyde (0.215 g, 2 mmol) was added. The reac-
tion mixture was heated under reflux for 4 h. Then it was gradually
cooled to room temperature. The solid that formed was recrystal-
supramolecular helicates [5]. Metal complexes bearing these
ligands have biochemical, analytical, antimicrobial, antifungal,
antitumor, therapeutic, herbicidal and industrial applications [6].
They are also useful as ionophores in ion-selective electrode stud-
ies [7].
1
lized from methanol. Yield, 0.225 (70%); mp 120 °C. H NMR
(200 MHz, CDCl
3
, TMS): d 8.67 (d, 4H), 8.25 (s, 2H), 7.58 (d, 4H),
1
3
3.62 (t, 4H), 1.69 (t, 4H), 1.36 (s, 8H). C NMR (200 MHz, CDCl
3
,
Copper(I) complexes have been widely studied because of pro-
viding suitable models for the representation of several enzymatic
sites as well as active intermediates in organic synthesis [8]. The
copper(I) complexes show unusually diverse geometries and stoi-
chiometries because of the relatively small energy difference
between the various polymorphs depending on synthetic condi-
tions such as ligand, anion and solvent [9]. As a part of our ongoing
efforts [10], in preparing interesting materials of Cu(I) with various
novel polydentate imio-pyridyl ligands we have synthesised three
TMS): d 159.18, 149.41, 148.59, 56.90, 31.83, 29.27, 26.63.
FTIR/cm (KBr): 2932(w), 2902(w), 1979(w), 1642(vs), 1597(s),
1556(s), 1466(m), 1419(s), 1389(w), 1325(s), 1283(s), 1230(s),
À1
1064(m), 1037(m), 954(w), 850(m), 822(s), 723(s), 641(vs),
+
523(s). ESI MS: 323.45 (LH , 100%). Anal. Calc. for C20
H
26
N
4
: C,
74.50; H, 8.13; N, 17.38. Found C, 74.55; H, 8.09; N, 17.39%. UV–
3
À1
À1
VIS: kmax/nm (
e
3
/dm mol cm )(CH OH): 251 (38,600); 280
(23,450).
I
1
I
2
1
mixed ligand copper(I) complexes [Cu
2
Cl
2
(L )(PPh
3
)
4
]
(1),
Synthesis of [Cu
Cl
2
(L ) (PPh
3
)
4
] (1)
1
] (2) and [CuI
1
[
CuI
2
Br
2
(L ) (PPh
3
)
4
2
(
l-I)
2
(
l-L ) (PPh ) ]
3 2 n
(3) of triph-
1
enylphosphine and polydentate imino-pyridyl ligand L (Scheme 1).
We have examined the structural diversity, photo-physical, electro-
chemical properties and catalytic activity (for the synthesis of
PPh
chloride (0.025 g, 0.25 mmol) in 15 ml CH
for 1 h. A colourless precipitate formed, to which the ligand L
(0.081 g, 0.25 mmol) and CHCl (3 ml) were added. The mixture
3
(0.066 g, 0.25 mmol) was added to a solution of copper(I)
3
CN, followed by stirring
1
2-substituted benzoxazole) of the ternary complexes 1, 2 and 3.
3
The influence of halide ion in the nuclearity and bonding in the mixed
ligand complexes described here is not common in the literature
was stirred for 10 min. Yellow coloured compound appeared. It
was filtered and dried in air. Single crystals were obtained by slow
diffusion of hexane to the dilute solution of the compound in
[
11,12].
À1
dichloromethane. Yield, 0.121 g (62%). FTIRcm (KBr): 3049(m),
2
1
5
7
925(m), 2845(w), 2369(w), 1633(m), 1599(m), 1474(s),
429(vs), 1316(w), 1089(s), 1022(m), 829(m), 750(vs), 693(vs),
Experimental section
I
1
2 2 3 4
12(vs), 409(w). Anal. found (calc. for [Cu Cl (L ) (PPh ) ]: C,
Materials and physical measurements
0.40 (70.48%); H, 5.52 (5.53%); N, 3.57 (3.58%), Cu, 8.09 (8.04%).
All chemicals used in this study were purchased from Aldrich
chemical company, USA and Acros chemical company, USA and
used without further purification unless otherwise mentioned.
Tetrabutyl ammonium perchlorate (TBAP) used for electrochemical
work is prepared as reported in the literature [13]. Methanol is
purified using the established method [14]. The melting point
was determined by an electro-thermal IA9000 series digital melt-
ing point apparatus and is uncorrected. Microanalyses were carried
out using a Perkin–Elmer 2400II elemental analyzer. Infrared (IR)
spectra and solution electronic spectra were recorded on Nicolet
Magna-IR (Series II) and Shimadzu UV-160A spectrophotometers
I
1
2 2 3 4
Synthesis of [Cu Br (L )(PPh ) ] (2)
PPh
bromide (0.036 g, 0.25 mmol) in 15 ml CH
for 1 h. A colourless precipitate formed, to which the ligand L
0.081 g, 0.25 mmol) and CHCl (10 ml) were added. The mixture
3
(0.066 g, 0.25 mmol) was added to a solution of copper(I)
3
CN, followed by stirring
1
(
3
was stirred for 30 min. Yellow coloured compound appeared. It
was filtered and dried in air. Single crystals were obtained by slow
diffusion of hexane to the dilute solution of the compound in chlo-
roform. Yield, 0.118 g (57%). FTIR (KBr pellet, cm ): 3049(m),
928(m), 2845(w), 2369(w), 1633(m), 1609(m), 1476(s),
429(vs), 1316(w), 1089(s), 1022(m), 829(m), 756(vs), 693(vs),
À1
1
13
31
2
1
5
6
respectively. H NMR, C and P NMR and Electrospray ionization
mass (ESI-MS) measurements were made using a Bruker Advance
I
1
12(vs), 409(w). Anal. found (calc. for [Cu
6.63 (66.64%); H, 5.23 (5.22%); N, 3.38 (3.39%), Cu, 7.66 (7.67%).
2 2 3 4
Br (L )(PPh ) ]: C,
4
00 MHz NMR spectrometer and Finnigan LCQ Decaxp MAX mass
UV–Vis: (CH
2
2
Cl ) [kmax, nm]: 402, 390.
I
2
1
Synthesis of [Cu
(
l-I)
2
(
l
-L ) (PPh
3 2
) ](3)
HC
N
N
(CH )n
N
To a solution of triphenylphosphine (0.262 g, 1 mmol) in CH
50 ml), solid cuprous iodide (0.19 g, 1 mmol) was added. The reac-
tion mixture was stirred for 1 h to obtain a white turbid solution.
3
CN
2
(
1
N
CH
L , n=8
1
3
Then the ligand L (0.322 g, 1 mmol) in 20 ml CHCl was added
drop-wise with constant stirring at room temperature to give a
clear yellowish solution. Then the reaction mixture was stirred
Scheme 1. Ligand system used in the study.