Spectral and magnetic properties and bio-activity of copper(II) clofibriates Part I. Crystal and molecular structure of trans-Cu(clofibriate)2(nicotinamide)2

Article abstract of DOI:10.1016/S0020-1693(00)00170-5

New copper(II) clofibriate (clof) Cu(clof)₂ and its compounds of composition Cu(clof)₂L₂ (where L = nicotinamide (na) or ronicol (ron)) and Cu(clof)₂-caffeine are reported. The characterizations were based on elemental analysis, electronic and EPR spectra, and magnetic susceptibility measurements over the temperature range 4.5-300 K. The crystal and molecular structure of Cu(clof)₂(na)₂ has been determined. The copper(II) atom is bonded in a trans square-planar arrangement by two N atoms of two nicotinamide molecules and one carboxylate oxygen atom from each of two clofibriate anions. The remaining two carboxylate oxygen atoms of the anions at the axial positions completed a tetragonal-bipyramidal geometry. On the basis of spectral and magnetic properties structures of the compounds were proposed. The antimicrobial effects have been tested on various strains of bacteria, yeasts and filamentous fungi. (C) 2000 Elsevier Science S.A.

Full text of DOI:10.1016/S0020-1693(00)00170-5

www.elsevier.nl/locate/ica
Inorganica Chimica Acta 308 (2000) 1–7
Spectral and magnetic properties and bio-activity of copper(II)
clofibriates
Part I. Crystal and molecular structure of
trans-Cu(clofibriate)2(nicotinamide)2
a,
a
b
a
´
Milan Meln´ık *, Marian Koman , Daniela Hudecova´ , Ja´n Moncol ,
b
Barbora Dudova´ , Tadeusz Glowiak c, Jerzy Mrozin´ski c, Clive E. Holloway d
a Department of Inorganic Chemistry, Slo6ak Technical Uni6ersity, SK-81237 Bratisla6a, Slo6ak Republic
b Department of Biochemistry and Microbiology, Slo6ak Technical Uni6ersity, SK-81237 Bratisla6a, Slo6ak Republic
c Institute of Chemistry, Wroclaw Uni6ersity, PL-50383 Wroclaw, Poland
d Department of Chemistry, York Uni6ersity, Toronto, Canada, M3J 1P3
Received 30 December 1999; accepted 5 May 2000
Abstract
New copper(II) clofibriate (clof) Cu(clof)2 and its compounds of composition Cu(clof)2L2 (where L=nicotinamide (na) or
ronicol (ron)) and Cu(clof)2–caffeine are reported. The characterizations were based on elemental analysis, electronic and EPR
spectra, and magnetic susceptibility measurements over the temperature range 4.5–300 K. The crystal and molecular structure of
Cu(clof)2(na)2 has been determined. The copper(II) atom is bonded in a trans square-planar arrangement by two N atoms of two
nicotinamide molecules and one carboxylate oxygen atom from each of two clofibriate anions. The remaining two carboxylate
oxygen atoms of the anions at the axial positions completed a tetragonal-bipyramidal geometry. On the basis of spectral and
magnetic properties structures of the compounds were proposed. The antimicrobial effects have been tested on various strains of
bacteria, yeasts and filamentous fungi. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Crystal structures; Biological activity; Copper complexes; Clofibriate complexes
pyridine) has been prepared and studied by X-ray
analysis [2]. In this paper we investigate the preparation
1. Introduction
of caffeine (caf), nicotinamide (na) and ronicol {3-
pyridylcarbinol} (ron) compounds of copper(II) clofi-
briate. The complexes were characterized by elemental
analysis, electronic and EPR spectra, and magnetic
susceptibility measurements over the temperature range
4.5–300 K. The crystal and molecular structure of
Cu(clof)2(na)2 was determined. The X-ray data are
compared and discussed with those found in familiar
Cu(RCOO)2(LN)2 compounds with the CuO4N2 chro-
mophore [3].
Copper ions play a vital role in a number of widely
differing biological processes, and their interaction with
drugs administered for therapeutic reasons is of consid-
erable interest. Propionic acid and some of its deriva-
tives also play an important role in biological processes,
and a number of copper(II) propionates have been
investigated [1]. Clofibric acid {2-(4-chlorophenoxy)-2-
methylpropionic acid} is a derivative of propionic acid
for which only Cu(clof)2(2-ampy) (2-ampy=2-amino-
Bioactivity of the complexes was tested on Staphylo-
coccus aureus, Escherichia coli, Candida parapsilosis,
Candida albicans, Rhizopus oryzae, Botrytis cinerea, Al-
ternaria alternata and Microsporum gypseum.
* Corresponding author. Tel.: +42-59-325 622; fax: +42-54-493
198.
E-mail address: melnik@cvtstu.cvt.stuba.sk (M. Meln´ık).
0020-1693/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(00)00170-5

2
M. Meln´ık et al. / Inorganica Chimica Acta 308 (2000) 1–7
2. Experimental
Blue compounds of composition Cu(clof)2(LN)2
(L=nicotinamide or ronicol (3-pyridylcarbinol)) were
prepared by adding LN in excess to a methanol solu-
tion of Cu(clof)2 and boiling. The reaction mixture was
filtered off and left to stand at r.t.
The blue impure products were recrystallized from
methanol to give air-stable crystals. Anal. Found: C,
51.8; H, 4.4; Cu, 8.7; N, 7.7. Anal. Calc. for Cu-
(clof)2(na)2: C, 52.28; H, 4.39; Cu, 8.64; N, 7.62%.
Anal. Found: C, 57.5; H, 4.6; Cu 9.0; N, 4.0. Anal.
Calc. for Cu(clof)2(ron)2: C, 57.60; H, 4.55; Cu 8.96; N,
3.95%.
2.1. Preparati6e
Sodium clofibriate solution was prepared from an
aqueous solution of 0.40 g NaOH (0.01 mol) by addi-
tion of 2.15 g (0.01 mol) of clofibric acid followed by
boiling. The partially evaporated solution was filtered
hot and the filtrate left at room temperature (r.t.).
White sodium clofibriate slowly precipitated, was iso-
lated and dried at r.t. The anhydrous salt of copper(II)
clofibriate was prepared by reaction of an aqueous
solution of sodium clofibriate (2.37 g, 0.01 mol, pH
adjusted to 4.5–5.0, using the free acid) with an
aqueous solution of copper(II) sulfate in the molar
ratio 2:1. The solution was left to crystallize at r.t. The
green–blue precipitate was collected, washed with cold
water and dried at r.t. Anal. Found: C, 49.1; H, 4.2, Cu,
12.9. Anal. Calc. for Cu(clof)2: C, 48.94; H, 4.40; Cu,
12.94%.
The caffeine complex was prepared by adding the
ligand (caf, 1.94 g, 0.01 mol) to copper(II) clofibriate
(0.01 mol) in hot methanol with a small amount of the
free acid. The mixture was stirred, filtered and left to
cool and stand at r.t. A green product precipitated, was
collected and recrystallized from methanol to give air-
stable green microcrystals. Anal. Found: C, 50.0; H,
4.35; Cu, 9.25; N, 8.2. Anal. Calc. for Cu(clof)2(caf): C,
49.10; H, 4.4; Cu, 9.28; N, 8.18%.
2.2. Spectroscopic studies
Electronic spectra in the region 10–28 kK were mea-
sured with a Perkin–Elmer 450 spectrophotometer us-
ing a Nujol suspension. EPR spectra of microcrystalline
samples were run on a Varian model E4 spectrometer
at r.t.
2.3. Magnetic susceptibilities
Measurements were made in the range 4.5–300 K for
Cu(clof)2(na)2 and 79–300 K for all remaining com-
pounds by the Gouy method using mercury tetrathio-
cyanatocobaltate(II) as a calibrant [4]. The molar
susceptibilities were corrected for diamagnetism using
Pascal’s constant [5] and t.i.p. (Na) of 60×10−6 cm3
mol−1 per copper atom. The effective magnetic mo-
ments were calculated from the expression
Table 1
Crystal data and structure refinement for Cu(clof)2(na)2
veff=2.83 (corr×T)0.5
Empirical formula
Formula weight
Temperature (K)
C16H16ClCu0.5N2O4
367.53
293(2) K
M
2.4. Crystallography
,
Wavelength (A)
0.71073
Crystal system
Space group
Unit cell dimensions
monoclinic
P21/c
Data collection and cell refinement were carried out
using Kuma KM4 diffractometer software [6]. Intensity
data were corrected for Lorenz and polarization fac-
tors. The structure was solved by the heavy atom
method with SHELXS-86 [7], and subsequent Fourier
synthesis using SHELXL-97 [8], anisotropic thermal
parameters were refined for all non-hydrogen atoms.
Geometrical analysis was performed using SHELXL-97
[8]. The structure was drawn using ORTEP [9]. The final
parameters after refinement are summarized in Table 1.
Selected inter-atomic distances and bond angles are
given in Table 2.
,
a (A)
13.961(3)
10.518(2)
11.857(2)
108.16(3)
1654.4(6)
4
1.476
2.878
,
b (A)
,
c (A)
i (°)
3
,
Volume (A )
Z
Dcalc (Mg m−3
)
Absorption coefficient (mm−1
F(000)
)
758
Crystal size (mm)
2q Range for data collection (°)
Index ranges
0.15×0.15×0.10
6.1–58.2
−185h518, −145k57,
−165l516
Reflections collected/unique
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I\2|(I)]
R indices (all data)
11 004/3871 [Rint=0.0303]
full-matrix least-squares on F2
3623/0/278
2.5. Bio-tests
1.096
The antimicrobial action of the compounds under
investigation was evaluated by a microdilution method
[10] using G+ bacteria S. aureus (CCM 3824). The
effects of these compounds on the yeasts C. parapsilosis
and C. albicans (isolated from human patients) were
R=0.0461, wR2=0.1153
R=0.0489, wR2=0.1192
Largest difference peak and hole 0.588 and −0.612
−3
,
(e A
)

M. Meln´ık et al. / Inorganica Chimica Acta 308 (2000) 1–7
3
Table 2
Selected bond lengths (A) and angles (°) for Cu(clof)2(na)2
was added to 1 ml of cell suspension (A600=0.20), and
the cells were preincubated for 10 min with intensive
aeration at 37°C. 5 ml of [14C] precursors were then
added to the tubes. The specific radioactivity of stock
a
,
CuꢀO(1)
CuꢀO(2)
O(2)ꢀC(1)
N(1)ꢀC(11)
1.994(2
2.614(2)
1.246(2)
1.345(2)
CuꢀN(1)
O(1)ꢀC(1)
N(1)ꢀC(15)
1.995(2)
1.280(2)
1.348(3)
solutions was [8-14C]adenine 0.25 Ci per 10 mg ml−1
,
l-[U-14C]leucine 0.1 Ci per 80 mg ml−1. The incubation
with [14C] precursors lasted for 1 h. The tubes were
transferred to an ice-bath and their contents were pre-
cipitated with 1 ml of 10% ice-cold TCA. The precipi-
tates were filtered through membrane filters (Sartorius
0.45 mm) and the radioactivity was assayed (Scintilla-
tion counter Rack-Beta, LKB).
O(1)ꢀCuꢀO(1)c1 180.0
O(1)ꢀCuꢀN(1)
88.30(6)
180.0
120.1(2)
118.8(2)
O(1)ꢀCuꢀN(1)c1 91.70(6)
N(1)ꢀCuꢀN(1)c
C(11)ꢀN(1)ꢀCu
C(11)ꢀN(1)ꢀC(15)
C(15)ꢀN(1)ꢀCu
O(2)ꢀC(1)ꢀO(1)
121.0(2)
122.5(2)
a Symmetry transformations used to generate equivalent atoms:
c1 −x, −y, −z+1.
determined by the macrodilution method in L-shaped
tubes [11]. The cultures of the bacteria and yeasts were
incubated under vigorous shaking.
The efficiency of prepared derivatives on filamentous
fungi R. oryzae (obtained from the Collection of Micro-
organisms of the Slovak Technical University; B.
cinerea (CCMF-16); A. alternata (CCMF-128) and M.
gypseum (isolated from human patients), were tested by
macrodilution technique on solidified broth medium
during static culturing [11].
Chromatographically pure compounds were dis-
solved in dimethyl sulfoxide, its final concentration
never exceeded 1.0 vol% in either control or treated
samples. Concentration of solutions, 1.25–5 mmol l−1
for bacteria and yeasts and 1.25–10 mmol l−1 for
filamentous fungi, was used in experiments.
The antimicrobial activity was characterized by the
IC50 values (concentration of a derivative which in
comparison to the control inhibits the growth of mi-
croorganisms to 50%) and MIC values (minimal in-
hibitory concentration of a derivative which inhibits
microbial growth by 100%). The IC50 and MIC values
were read from toxicity curves.
3. Results and discussion
The electronic spectrum of Cu(clof)2 shows a broad
symmetrical band at about 14 kK due to d–d transi-
tions and a shoulder at about 24.5 kK due to charge
transfer transition. The electronic spectrum of Cu-
(clof)2(caf) shows a band at 14.5 kK, which was iden-
tified as a d–d transition of the copper(II), and a
shoulder at 27.0 kK. The shoulder is characteristic of
the dimeric system of copper(II) acetate with an antifer-
romagnetic interaction [12]. The solid-state spectra of
Cu(clof)2(na)2 and Cu(clof)2(ron)2 exhibit a broad lig-
and field band, maximum at about 15.4 kK, and a
shoulder at about 13.0 kK for the former and 15.8 kK
for the latter. These types of d-d spectrum are typical of
a tetragonal arrangement around copper(II) corre-
sponding to electron transfer from the one-electron
orbital state dx
[13].
2
2
The EPR spe−ctyrum of Cu(clof)2 is of the isotropic
type with giso=2.09. The EPR spectrum of Cu-
(clof)2(na)2 is of the axial type with gÞ=2.04, gꢀ=2.30
and gav=2.13. This points to a structure having a value
of effective spin S=1/2 and a ground state dx
2. All
2
−y
MIC experiments on subculture dishes were used to
assess the minimal microbicidal concentration (MMC).
Subcultures were prepared separately in Petri dishes
containing competent agar medium and incubated at
30°C for 48 h (bacteria, yeasts) and at 25°C for 96 h
(filamentous fungi). The MMC values were taken as the
lowest concentration that showed no visible growth of
microbial colonies in the subculture dishes.
The effect of Cu(clof)2(caf) on energy requiring pro-
cesses in P. aeruginosa was determined by the incorpo-
ration of [14C] precursors into the nucleic acids and
proteins. The microorganism P. aeruginosa 9/93 was
isolated from a patient suffering from nosocomial infec-
tion. The bacterial suspension (0.4 ml, A600=0.5) was
inoculated into 10 ml of the synthetic medium and was
incubated under conditions of intensive aeration at
the compounds thus seem to possess an octahedral
stereochemistry with differing degrees of tetragonal dis-
tortions about the copper(II) atom.
The EPR spectrum of Cu(clof)2(caf) showed an ab-
sorption band typical of an axially symmetric dimeric
species [14]. The powder of the compound shows ab-
sorption features at both low (HZ1) and high (HZ2)
fields, and an asymmetric absorption near 4500 G
(HT2). One is missing, because ꢁDꢁ\hw at the X-band
frequency. The spectrum can be interpreted using a spin
Hamiltonian for axial symmetry
H=gꢀiHZSZ+gÞ(HXSX+HYSY)+D(S2Z+2/3)
with S=1 for the thermally accessible triplet state and
the other symbols have their usual meaning. The values
obtained for the spin Hamiltonian parameters are:
gÞ=2.06; gꢀ=2.32, gav=2.15; ꢁDꢁ=0.382 cm−1. The
ꢁDꢁ value is large compared to the magnetic quantities
(ꢀ3.00 G), but small compared to the vibration fre-
37°C up to the logarithmic phase of growth (A600
0.20). 100 ml of Cu(clof)2(caf), dissolved in dimethyl
sulfoxide (final concentration ranging 0–5 mmol l−1
=
)

4
M. Meln´ık et al. / Inorganica Chimica Acta 308 (2000) 1–7
Table 3
Magnetic data for Cu(clof)2 (1) and Cu(clof)2(ron)2 (2)
1
2
T (K) a

corr×105
veff (BM)

corr×105
M
veff (BM)
M
(cm3 mol−1
)
(cm3 mol−1
)
79
115
157
190
247
273
299
314
254
230
204
174
160
143
1.41
1.53
1.70
1.76
1.85
1.87
1.85
493
336
275
228
182
164
147
1.77
1.76
1.86
1.86
1.90
1.89
1.88
a Selected from 20 experimental points; (1) Mr=490.83; diamag-
netic correction +Na×10−6 cm3 mol−1; D=253; (2) Mr=709.03;
D=384.
Fig. 2. Magnetic susceptibility ( ) and magnetic moment (ꢀ) versus
temperature for Cu(clof)2(caf).
quencies. The values are comparable to those found in
dimeric copper(II) carboxylates [1].
The magnetic susceptibility results for polycrystalline
samples of Cu(clof)2, Cu(clof)2(ron)2, between 79 and
300 K, and Cu(clof)2(na)2 between 4.5 and 300 K, obey
the Curie–Weiss law
the Curie (C) constant of 0.64(1) cm3 mol−1 and Weiss
([) constant of −127(5) K for the former differ from
the values of 0.487(5) cm3 mol−1 and −23.6(6) K,
respectively observed for the latter. The negative Weiss
constants indicate an antiferromagnetic interaction in
both derivatives, being much greater in the former than
the latter.

corr=C/(T−[)
M
where the Curie constant C=Ng2i2S(S+1)/3K and
S=1/2. The temperature variation of magnetic suscep-
tibility and magnetic moments for Cu(clof)2 and Cu-
(clof)2(ron)2 are given in Table 3. The values of the
magnetic moment at 299 K of 1.85 and 1.8 BM,
respectively, are well over the 1.73 BM for one un-
paired electron, indicating spin–orbital contributions
which are somewhat larger in Cu(clof)2(ron)2 than in
Cu(clof)2. As can be seen, the magnetic moments are
dependent on temperature in both compounds, decreas-
ing as the temperature drops. The change is greater for
Cu(clof)2 than for Cu(clof)2(ron)2. The best values of
The temperature variation of magnetic susceptibility
and magnetic moment for Cu(clof)2(na)2 are shown in
Fig. 1. For this derivative the magnetic moment of 1.81
BM at 300 K drops to 1.60 BM at 4.5 K. The best
values of the C and [ are 0.411(5) cm3 mol−1 and
−1.4(1) K, respectively. The very small negative values
of the Weiss constant indicate a very weak antiferro-
magnetic interaction. The molar susceptibility of Cu-
(clof)2(caf) and magnetic moment temperature depen-
dence are shown in Fig. 2. The temperature variable
magnetic susceptibility data can be described by the
equation:
Fig. 3. Perspective view of complex [Cu(clof)2(na)2], with the atom
numbering scheme. Thermal ellipsoids are drawn at the 50% proba-
bility level.
Fig. 1. Magnetic susceptibility ( ) and magnetic moment (ꢀ) versus
temperature for Cu(clof)2(na)2.

M. Meln´ık et al. / Inorganica Chimica Acta 308 (2000) 1–7
5
Fig. 4. Growth of S. aureus in the presence of copper(II) compounds and the ligands in concentration of 5 mmol l−1. A: ꢀ, Hclof; ꢁ, Cu(clof)2;
", Cu(clof)2(ron)2; ꢂ, Cu(clof)2(caf); 2, Cu(clof)2(nia)2. B: +, ron; ×, caf; *, nia; , control (1% DMSO).

corr=Ng2i2/3kT(1/(1+1/3 e−2J/kT))
ably be supposed that the caffeine compound has a
dimeric structure Cu2(clof)4(caf)2 with a distorted
square-pyramid around each copper(II) atom. Each of
these is coordinated to four oxygen atoms of the clofi-
briate anions (in plane) in a syn–syn fashion, together
with a nitrogen atom of caffeine at the apex.
On the basis of the spectral and magnetic data, a
tetragonal bipyramidal geometry is deduced for remain-
ing compounds. It is suggested that in Cu(clof)2 the
clofibriate anions use both carboxylate oxygen atoms
M
was also corrected for t.i.p. of 60×10−6
corr
where 
M
cm3 mol−1 per copper(II) atom, and the other symbols
have their usual meaning. The spectroscopic splitting
factor gav=2.15 was obtained from the EPR spectrum
and used in the least-squares fitting procedure to give a
best-fit for −2J of 334910 cm−1 between the ther-
mally accessible singlet state (S=0) and triplet state
(S=1). This is similar to values found in related cop-
per(II) carboxylates [1]. From the above it may reason-
Fig. 5. Growth of E. coli in the presence of copper(II) compounds and the ligands in concentration of 5 mmol l−1. A: ꢀ, Hclof; ꢁ, Cu(clof)2;
", Cu(clof)2(ron)2; ꢂ, Cu(clof)2(caf); 2, Cu(clof)2(nia)2. B: +ron; ×caf; *, nia; , control (1% DMSO).

6
M. Meln´ık et al. / Inorganica Chimica Acta 308 (2000) 1–7
Table 4
Antifungal activity of copper(II) compounds and free by the numerical values of IC50 (mmol l−1) and MIC (mmol l−1
)
Compound
Filamentous fungi
Yeasts
R. oryzae
B. cinerea
A. alternata
M. gypseum
C. parapsilosis
C. albicans
IC50
MIC
IC50
MIC
IC50
MIC
IC50
MIC
IC50
MIC
IC50
MIC
Hclof
ron
caf
na
Cu(clof)2
Cu(clof)2(ron)2
Cu(clof)2(caf)
Cu(clof)2(na)2
\10
\10
10
\10
\10
5
\10
\10
\10
]10
\10
\10
5 a
6
\10
\10
\10
\10
\10
\10
10 a
7
\10
\10
\10
\10
\10
\10
3.3
5 b
\5
\5
\5
\5
\5
\5
\5
\5
\5
\5
\5
\5
\5
\5
4
\5
1.5
2.2
\5
\5
\5
\5
\5
\5
5 a
\10
6.2
\10
\10
4
\10
10
\10
\10
4
\10
B2.5
\10
B2.5
1.4
\10
52.5 b \5
\10
52.5 b 2.5
55 b
3.5
52.5 b 2.5
55 b
2.7
\5
2.5
B1.25
3
3
\10 a B2.5
\10 a 2.5
B1.25 a
B2.5 a
\10
B2.5 a
5 a
a Microstatical effect.
b Microbicidal effect.
,
,
for bonding to the copper(II) atoms in the polymeric
structure. In the ron adduct in addition to the clofibriate
anions both a pyridine ring atom and a carbinol oxygen
atom act as donors to copper(II), as in the derivative
Cu(niflumate)2(ron)2 for which the X-ray structure is
known [15]. In this example the ron groups are ambiden-
tate, linking the copper(II) atoms into infinite chains.
The Cu(clof)2(na)2 was also studied by the X-ray
method and its crystal structure is shown in Fig. 3. As
can be see the copper(II) atom is bonded in a trans
square-planar arrangement to the nitrogen atoms of two
in the sequence: 2.00 A versus 54.2° (four-)B2.02 A
,
versus 75.0° (five-)B2.06 A versus 89.3° (six-membered
OꢀCuꢀO metallocyclic ring). The difference between two
CuꢀO bond distances of the respective chelate, decrease
in the same sequence: 0.76 A (mean 1.97 and 2.73
A)\0.40 A (1.94 and 2.34 A)\0.265 A (2.01 and 2.275
A).
Antibacterial activities of copper(II) compounds as
well as of free ligands are shown in Figs. 4 and 5. As can
be see in Figs. 4 and 5 the ligands (except caf) have almost
no influence on the growth of the respective bacteria.
Clofibrinic acid has an approximately 20% of inhibition
(Figs. 4 and 5). An expressive increase of anti-
microbial activity was attained for copper(II) clofibriates.
The inhibition activity against the G+ bacterium S.
aureus (Fig. 4) increases in the order: naBronBcafB
Hclof B Cu(clof)2(na)2 B Cu(clof)2(ron)2 B Cu(clof)2-
(caf)BCu(clof)2; and against G− bacteria E. coli in the
order: naBronBHclofBCu(clof)2BcafBCu(clof)2-
(ron)2BCu(clof)2(na)2BCu(clof)2(caf).
,
,
,
,
,
,
,
nicotinamide molecules (CuꢀN(1)=1.995(2) A) and one
carboxylate oxygen atom from each of two clofibriate
,
anions (CuꢀO(1)=1.994(2) A. The remaining two car-
boxylate oxygen atoms which are weakly bonded to the
,
copper (CuꢀO(2)=2.614(2) A) and the direction of the
CuꢀO(2) bonds lie at 60.1° from the normal to the
CuO2N2 plane completed a tetragonal-bipyramidal coor-
dination. The copper(II) atom lies on a crystallographic
center of symmetry.
Bond distances and angles are listed in Table 2. The
in-plane O(1)ꢀCuꢀN(1) angles are 88.30(6) and 91.70(6)°
and out-off-plane O(2)ꢀCuꢀN(1) angles are 92.30(6) and
87.70(6)°, but because of the small bite of the carboxylate
group the angle between the short CuꢀO(1) bond the long
CuꢀO(2) bond is only 55.49(5)°. The oxygen atom which
is most strongly bonded to the copper(II) atom has a
As can be seen, the binuclear Cu(clof)2(caf) is most
active against both types of bacterium G+ and G−, while
a polymeric Cu(clof)2 is dominant against G+ bacteria
but not against G− bacteria.
Antifungal activities of the compounds are summa-
rized in Table 4. As can be seen, the inhibition activities
increase in the sequences: Hclof=ron=na=Cu-
(clof)2Bcaf B Cu(clof)2(ron)2 B Cu(clof)2(caf) B Cu-
(clof)2(na)2 against R. oryzae; na=ron=Cu(clof)2B
Hclof B caf B Cu(clof)2(ron)2 B Cu(clof)2(caf) B Cu-
(clof)2(na)2 against B. cinerea; na=ron=Cu(clof)2B
caf B Hclof B Cu(clof)2(ron)2 B Cu(clof)2(caf) B Cu-
(clof)2(na)2 against A. alternata; na=ron=HclofB
Cu(clof)2(na)2 B caf B Cu(clof)2(caf)=Cu(clof)2 B Cu-
(clof)2(ron)2 against M. gypseum; and na=ron=caf=
Hclof B Cu(clof)2(na)2 B Cu(clof)2(caf) B Cu(clof)2
against C. parapsilosis.
,
C(1)ꢀO(1) bond distance of 1.280(2) A which is longer,
,
than the other C(1)ꢀO(2) bond, 1.246(5) A, of the
carboxylate unit.
There are over 20 examples [3] of the general formula
Cu(RCOO)2(LN)2 in which bidendate RCOO ligands
with two monodendate N donor ligands build up a
tetragonal-bipyramidal coordination about the Cu(II)
atom (CuO4N2) with a different degree of distortion. In
this series is a relationship between CuꢀL bond distances
and metallocyclic rings. While CuꢀN bond distance
elongated with an increasing size of metallocyclic ring,

M. Meln´ık et al. / Inorganica Chimica Acta 308 (2000) 1–7
7
In general, the inhibition activity of the Cu(clof)2(na)2
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,
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Acknowledgements
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This study was supported by the Grant Agency of the
Slovak Ministry of Education (Reg. No. 95/5195/199,
95/909 and 1/4203/97).
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