1-(3-Chlorophenyl)-4-(3-phenylseleno propyl) piperazine (L); synthesis, spectroscopic characterization, DFT studies, antimicrobial evaluation and its reactivity toward group 12 metal chlorides

Article abstract of DOI:10.1080/00958972.2018.1489126

C₆H₅Se^?Na⁺ (generated in situ by NaBH₄ reduction of (C₆H₅Se)₂) on reaction with ClC₃H₆C₄H₈N₂ClC₆H

Full text of DOI:10.1080/00958972.2018.1489126

Journal of Coordination Chemistry
ISSN: 0095-8972 (Print) 1029-0389 (Online) Journal homepage: http://www.tandfonline.com/loi/gcoo20
1-(3-Chlorophenyl)-4-(3-phenylseleno propyl)
piperazine (L); Synthesis, spectroscopic
characterization, DFT studies, antimicrobial
evaluation and its reactivity towards group 12
metal chlorides
Muzzaffar A. Bhat, Shabir H. Lone & Sanjay K. Srivastava
To cite this article: Muzzaffar A. Bhat, Shabir H. Lone & Sanjay K. Srivastava (2018): 1-(3-
Chlorophenyl)-4-(3-phenylseleno propyl) piperazine (L); Synthesis, spectroscopic characterization,
DFT studies, antimicrobial evaluation and its reactivity towards group 12 metal chlorides, Journal of
Coordination Chemistry
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Publisher: Taylor & Francis
Journal: Journal of Coordination Chemistry
DOI: http://doi.org/10.1080/00958972.2018.1489126
1-(3-Chlorophenyl)-4-(3-phenylseleno propyl) piperazine (L); Synthesis,
spectroscopic characterization, DFT studies, antimicrobial evaluation and its
reactivity towards group 12 metal chlorides
MUZZAFFAR A. BHAT*†‡, SHABIR H. LONE§ and SANJAY K. SRIVASTAVA*†
†School of Studies in Chemistry, Jiwaji University, Gwalior 474011, India
‡Department of Chemistry, Islamic University of Science and Technology, Awantipora, Kashmir, 192122, India
§Department of Chemistry, Govt Degree College Anantnag, Kashmir 192101, India
C6H5Se-Na+ (generated in situ by NaBH4 reduction of (C6H5Se)2) on reaction with
ClC3H6C4H8N2ClC6H5 under N2 atmosphere results in C6H5SeC3H6C4H8N2ClC6H5 (L) as a
cream-colored solid. Its 1:1 metal complexes having the general formula [MLX2], where M =
Zn, Cd, Hg and X = Cl, have been prepared. Ligand L and its complexes 1-3 are characterized on
the basis of physico-chemical and spectral (FT-IR, ESI Mass, 1H, 13C, DEPT 135° 13C {1H} and
77Se{1H} NMR) studies. IR spectroscopy revealed that L is coordinated solely through selenium
and nitrogen to zinc, cadmium and mercury ions forming a six-membered chelate ring around
M(II) ions. Elemental analysis measurements along with 1H, 13C, DEPT 135o 13C {1H} and ESI
mass data also confirm the bidentate coordination mode of the ligand. Moreover, the
coordination from selenium atom is also supported by the downfield shift of signal in
77Se{1H} NMR spectroscopy. Using DFT-based optimization of structures, the HOMO-LUMO
energy gaps and molecular electrostatic potential (MEP) surface of ligand L and complexes 1-3
were theoretically calculated at the B3LYP/LANL2DZ level of theory. Ligand L and complexes
1-3 display significant antibacterial and antifungal activity.
Keywords: Reduction; Selenium; Bidentate; Coordination; DFT; Biological activity
*Corresponding authors. Email: muzzaffarbhat9@gmail.com, muzzaffarbhat9@yahoo.com (M.A. Bhat);
sksrivas7@yahoo.com (S.K. Srivastava)
1

1. Introduction
Group 12 metals (Zn, Cd, Hg) are considered to be the most covalent and chalcophilic in the
periodic table. The chemistry of group 12 metal chalcogenides has been extensively studied due
to their applications in the field of nanomaterials [1] and opto-electronics [2]. Due to their
importance, the preparation and structural characterization of group 12-16 complexes as single-
source stoichiometric precursors have continued to draw the attention of chemists. Various
research groups have reported that [M(ER)2] complexes (M = Zn, Cd or Hg; E = S, Se or Te; R =
aryl) can be utilized as such precursors [3]. However, these compounds are generally polymeric
in the solid state, very difficult to isolate in the crystalline form, relatively insoluble in
hydrocarbon solvents and therefore, very difficult to be purified and characterized [4].
Organoselenium chemistry has been exploited to present an extensive range and high diversity of
products that find an inevitable place in the area of synthetic applications [5, 6]. In addition,
organoselenium compounds are known to be suitable antioxidants because of their unique ability
to imitate the enzymatic activities of glutathione peroxidase (Gpx) that catalyzes the
decomposition of hydroperoxides in various biochemical reactions [7, 8]. Organoselenium
compounds containing selenium in bivalent oxidation state play a prominent role in coordination
chemistry [9, 10]. An extensive use of organoselenium compounds in semiconductors and Metal
Organic Chemical Vapor Deposition (MOCVD) techniques consign these compounds a
noticeable position in electronic chemistry [11, 12]. A number of methods [13-17] have been
developed to obtain an array of aryl/alkyl monoselenides and symmetrical diselenides [18-20].
Symmetrical dialkyl/diaryl monoselenides have also been prepared by the cleavage of
dialkyl/diaryl diselenides [21-23], while other methods use transition metal complexes [24-26].
Synthesis, ligation behavior and applications of N-{2-(4-
methoxyphenyltelluro)ethyl}morpholine with palladium(II), half-sandwich ruthenium(II)
complexes of N-{2-(arylchalcogeno)ethyl}morpholine as useful catalysts for oxidation of
alcohols and rhodium(III) complexes of N-{2-(arylseleno/telluro)ethyl}morpholine as catalysts
suitable for transfer hydrogenation of ketones has been reported by Singh and co-workers.
Recently, the same group carried out the synthesis and structural chemistry of N-{2-
(arylthio/seleno)ethyl}morpholine/piperidine-palladium(II) complexes as potent catalysts for the
Heck reaction [27].
2

Our continuing interest in the chalcogen-based ligands [28-33] prompted us to report the
novel synthesis and coordination behavior of seleno-piperazine ligand containing nitrogen
donors in conjunction with selenium and thus the ligation behavior of (Se, N, N) type hybrid
donor ligands with group 12 metal halides.
2. Experimental
2.1. Materials and methods
1-(3-Chlorophenyl)-4-(3-chloropropyl)piperazine hydrochloride was procured from Sigma-
Aldrich (USA) and used as received. Solvents were dried and distilled before use by well-known
standard procedures [34]. The molar conductance of the compounds were measured at r.t.
(30±2 °C) using a dip-type conductivity cell (cell constant = 0.95) on an ELICO conductivity
meter model 127 in anhydrous dimethylsulfoxide (DMSO). The FT-IR spectra of the compounds
were recorded on a Nicolet Protége 460 FT-IR spectrometer (KBr, 4000-340 cm-1). 1H, 13C {1H},
DEPT 135o 13C {1H} and 77Se {1H} NMR spectra were recorded on a Bruker Spectrospin DPX-
300 NMR spectrometer at 300.13, 50.47, 50.47 and 57.24 MHz, respectively. ESI-mass spectra
were recorded on a WATERS-Q-TOF premier-HAB213 spectrometer. The samples (dissolved in
methanol and acetonitrile) were introduced into the ESI source through a syringe pump at the
rate 3 µL/min. The ESI capillary was set at 3.5 kV and the cone voltage was 40 V.
All the computations are carried out using GAUSSIAN 09 software [35]. The DFT
modeling method, using the hybrid B3LYP [36] functional was used to calculate L and
complexes 1-3 with the basis set combination 6-311 G(d,p) [37]. The antimicrobial activity was
performed against one bacterial and one fungal strain. The organisms selected were the Gram-
positive Staphylococcus aureus (NCIM2063, Sa) and the fungal strain Aspergillus niger (ATCC-
6275, An). The method employed to determine the MIC values was serial tube dilution method
[38] for ligand as well as complexes. 2.00 mg of each tested compound was placed in vials
separately and 2 mL of DMSO was added and a solution of the concentration 1.00 mg/mL was
obtained. Staphyllococus aureus was grown at 37 °C in nutrient agar medium and then diluted in
sterile nutrient broth medium to get a suspension containing about 107 cells/mL and finally used
as the inoculum. As much as 11 test tubes were taken, 9 of which were marked as T1, T2, T3, T4,
T5, T6, T7, T8 and T9 and the remaining two were assigned as TM (medium) and TMI
(medium+inoculum). 1 mL of nutrient broth medium was poured into all 11 test tubes. The tubes
3

were plugged with cotton and sterilized in an autoclave. The tubes were then cooled and 1 mL of
the sample solution was added in the first test tube and mixed well followed by transference of
1 mL of the contents to the second test tube; this process of serial dilution was done up to the
ninth test tube. 10 µL of properly diluted inoculum was added to each of the nine test tubes and
mixed well. 10 µL of the inoculum was added to the test tube TMI to observe the growth of the
organism in the medium used. To confirm the sterility of the medium the controlled test tube TM
containing only the medium was used. All the test tubes were incubated at 37 °C. The same
experiment was done with medium, DMSO, and inoculum without compound to ensure that the
DMSO has no inhibitory effect. The test tube number in which the first sign of growth of the
organism was observed was noted. The MIC was taken as that concentration used in the test tube
number just prior to the test tube number where the first sign of growth was observed. This was
done for all the compounds and ligand to calculate their MIC values. The same procedure was
done to assess the antifungal activity of the compounds except that Potato-Dextrose-Agar
medium was used.
2.2. Synthesis of 1-(3-chlorophenyl)-4-(3-phenylseleno propyl)piperazine (L)
To a stirred solution of diphenyl-diselenide (1.57 g, 5 mmol) and sodium hydroxide (0.040 g,
5 mmol) in aqueous THF (20 mL + 0.2 mL H2O) under dry nitrogen, NaBH4 (0.419 g, 11 mmol)
was added in pinches. The orange-yellow color of the diselenide disappeared within few
minutes. The resulting colorless sodium phenyl-selenoate solution was allowed to warm to room
temperature over 0.25 h. To the clear solution thus formed, 1-(3-chlorophenyl)-4-(3-
chloropropyl) piperazine hydrochloride (3.09 g, 10 mmol) was added in pinches. The reaction
mixture was stirred overnight at room temperature and then treated with 50 mL of 1 M NaOH
solution. Ligand L was extracted into chloroform from this basic solution. The extract was
washed with water, dried over anhydrous magnesium sulfate and concentrated under reduced
pressure to give a cream-colored viscous oil. It was repeatedly washed with hexane to remove
the unreacted diphenyl-diselenide. Solid cream product was precipitated by addition of 2-3 drops
of methanol to the viscous mass. It was filtered and dried in vacuo (scheme 1).
4

-
+
Se
Se
Cl
Se
Na
NaBH , N atm
4
2
N
N
+
Cl
THF
-NaCl
Cl
N
N
Se
L1
Scheme 1. Synthetic scheme and chemical structure of L.
2.3. Reaction of L with group 12 metal chlorides
In a representative experiment, to a solution of L (0.357 g, 1 mmol) in absolute ethanol and
anhydrous ZnCl2 (0.360 g, 1 mmol) in the same solvent, were stirred together at r.t. under dry
dinitrogen for about 4 h. The precipitated product was filtered and washed several times with
petroleum ether (60-80 °C). The product was dried under vacuo. Similar complexes were
prepared using anhydrous CdCl2 and HgCl2 (99.9% purity) as metal acceptors (scheme 2).
N
N
+ ZnCl2
Se
Cl
N
N
Se
Zn
Cl
Cl
Cl
MLX2
MX 2 + L
M= Zn
= Cd X= Cl (2)
= Hg (3)
(1)
Scheme 2. Synthesis of group 12 metal complexes.
5

3. Results and discussion
3.1. General
The analytical and physical data of L and 1-3 are in agreement with the 1:1 stoichiometry
(table 1). L is isolated as solid white product, stable at r.t. and not affected by atmospheric
oxygen and moisture. Complexes 1-3 are of 1:1 (donor:acceptor) stoichiometry and are solids,
soluble in common organic solvents.
3.2. Conductance
The molar conductance (ΛM) of L and 1-3 has been determined in DMSO 1 mM and the values
are given in table 1. Molar conductance of L and 1-3 have been found to be much lower than the
value expected for any electrolyte and hence these may be considered to behave as non-
electrolyte or non-ionic.
3.3. ESI Mass spectra
The ESI mass spectrum of L and complex 3 were recorded using methanol and acetonitrile as
solvents and important fragmentation patterns are given in table S1.
In the positive ESI mass spectrum of L, molecular ion peak at 395 with 50% of relative
abundance is in agreement with the proposed weight of the compound. Isotopic distribution
pattern of chlorine is also observed. The other peaks observed at m/z 240 and m/z 162 are due to
[L-(C6H5-Se)] and [L-(C6H5Se)-(C3H7)], respectively. Another fragment at m/z 85, due to
[L-(C6H5Se)-(C3H7)-(C6H5Cl)] with 90% of relative abundance, corresponds to the base peak.
These signals also exhibit the expected characteristic isotopic distribution pattern of chlorine
(figure S1).
In the ESI mass spectrum of 3, molecular ion peak is observed at m/z 670 with 20%
relative abundance, which is in agreement with the proposed molecular weight of the complex.
Another peak, observed at m/z 628 with 18% relative abundance, is due to [M-Cl] and at m/z
395 is due to the [(M-Cl-(HgCl)] as base peak with 100% relative abundance. Other fragments at
m/z 226 and m/z 197 are observed due to [(M-Cl-(HgCl)-C6H5SeCH2] and [(M-Cl-(HgCl)-
C6H5SeCH2-(C2H5))] (figure S2).
6

3.4. IR Spectra
Infrared (IR) spectra of L and complexes 1-3 have been recorded using KBr discs (table S2). In
the IR spectra of L, the bands due to ν(C-N) group appear at 1178 and 1106 cm-1. The band due
to ν(C-H)aromatic appears at 3082 cm-1, which shows the presence of phenyl group whereas
ν(C-H)aliphatic appears at 2854 cm-1. The band of the characteristic group ν(C=C) appears at
1618 cm-1. The band of low intensity at 498 cm-1 is assigned to ν(Se-C).
In complexes 1-3, the bands due to ν(Se-C) group were found slightly shifted to lower
frequency (481, 485 and 482 cm-1 for complexes 1, 2 and 3, respectively) and appeared at
483±2 cm-1 in comparison to L, which clearly shows that selenium is involved in coordination to
metal salts. Signals due to ν(C-N) group also shifted to lower frequency (1162, 1158 and
1155 cm-1 for 1, 2 and 3, respectively) and appeared around 1159±4 cm-1. The other
characteristic bands are ν(C-C)aliphatic, ν(C-H)aromatic and ν(C-H)aliphatic appearing at 1620±10,
3042±10 and 2854±5 cm-1, respectively. DFT assisted IR and experimental IR of ligand L
(figure S1) and complex 1 also displayed close agreement.
3.5. 1H NMR Spectra
1H NMR spectra of L and complexes 1-3 have been recorded in CDCl3 and DMSO-d6 and values
are given in table S3. In the 1H NMR spectra of L, two triplets appearing at 2.95-2.98 ppm and
2.46-2.50 ppm are assigned to Se-CH2 and CH2-N, respectively, while the multiplet at 1.88-
1.95 ppm is due to -CH2-. Piperazine ring protons appear as two triplets at 2.52-2.55 ppm and
3.28-3.46 ppm. Aromatic protons (Ar-H) attached to Se and Cl are as expected and found at
7.13-7.63 ppm as multiplets (figure S4).
In complexes 1-3, the signals due to CH2-N show deshielding by about ~0.2 ppm (2.54-
2.60, 2.57-2.68 and 2.47-2.60 ppm for complexes 1, 2 and 3, respectively), suggesting
participation of nitrogen in coordination to metal. However, the signals due to Se-CH2 and
aromatic protons show also deshielding (2.89-2.99, 2.97-3.11 and 2.92-3.09 ppm for 1, 2 and 3,
respectively) by about ~0.2 ppm relative to free ligand, indicating the involvement of Se also in
coordination to metal. -CH2- and aromatic protons remain almost at similar positions. The
signals due to N-CH2 merge with signals of DMSO-d6 in all complexes. Thus, L adopts a
bidentate coordination mode in complexes 1-3 (figures S5-S7). Theoretical and experimentally
calculated 1H NMR data for ligand L (figure S8) is in very close agreement with each other.
7

3.6. 13C {1H} NMR Spectra
13C {1H} NMR spectra of L and complexes 1-3 have been recorded in CDCl3 and DMSO-d6 and
values are given in table S4. In the 13C{1H} NMR spectrum of L, the signals at 27.55, 58.13 and
25.83 ppm are assigned to Se-CH2, CH2-N and -CH2-, respectively. Piperazine ring carbons
resonate at 53.19 and 48.82 ppm, respectively. Aryl carbons Ar-C (ortho, meta, para- to Se and
Se-Cipso) appear at 130.73, 128.94, 126.98 and 132.73 ppm, respectively. Cl-aryl ring carbons
resonate at 152.54, 114.01, 130.21, 115.90, 135.15 and 119.40 ppm (figure S9).
In complexes 1-3, the Se-CH2 signals are found deshielded (50.55, 45.15 and 45.23 ppm
for 1, 2 and 3, respectively) by 18-24 ppm with respect to free ligand, indicating the involvement
of Se in coordination to metal. The signals due to N-CH2 (57.19, 55.41 and 58.60 ppm for 1, 2
and 3, respectively) were also found deshielded which confirms the involvement of N also in
coordination to metal salts (figures S10-S12).
3.7. DEPT 135o 13C {1H} NMR
DEPT 135o 13C {1H} NMR spectra of L (figure S13) and complex 1 support the data obtained
from 13C{1H} NMR and further authenticate the formation of L and complexes. CH2 carbons of
piperazine, Se-CH2, N-CH2 and CH2 are antagonistic to CH carbons of two phenyl rings
(figure S14).
3.8. 77Se {1H} NMR Spectra
The 77Se{1H} NMR spectra of L and complexes 1 and 2 were recorded using CDCl3 and DMSO
as solvent and Me2Se as an internal standard. In the 77Se NMR (proton decoupled) spectra of L
(figure S15), a single peak is observed at δ = 289.74 ppm which is deshielded by 42-54 upon
complexation. The deshielding of the selenium atom in complexes supports the formation of
metal-selenium bond, which authenticates the findings of IR, 1H and 13C NMR spectra
(figure S16).
3.9. Optimization
The optimized structures as deduced from DFT using B3LYP/LANL2DZ level of theory are
shown in figure 1. For complexes 1-3, the geometry around M(II) atom is distorted tetrahedral as
8

revealed by bond angles. Selected bond lengths and angles of ligand L and complexes 1-3
theoretically calculated at the B3LYP/LANL2DZ are presented in tables 2 and 3.
3.10. Molecular electrostatic potential surface analysis
Molecular Electrostatic Potential (MEP) is useful for predicting molecular reaction behavior. It is
used to assess the molecular reactivity towards charged reactants and depict the hydrogen bond
interactions. MPE surfaces reveal essential characteristics like size, shape and variation of
electron density while correlating with dipole moment, partial charges, electronegativity, and
chemical reactivity sites located in the molecule. Figure 2 shows the MEP surface of ligand L
and complexes 1-3 that were calculated using DFT/B3LYP; LANL2DZ basis set. The pictorial
representation with rainbow-colored scheme of electrostatic potential for L lies in the range of
-2.970 a.u. to +2.970 a.u. and between -5.830 to +5.830 a.u., -5.524 to +5.524 a.u. and -4.913 to
+4.913 a.u. for complexes 1-3, respectively. In the ESP map for all compounds the region
surrounding the chlorine, nitrogen and selenium atoms appear to be darkest red that is one with
highest electron density.
3.11. Frontier molecular orbitals
Frontier molecular orbitals (FMO) (figure 3) determining the electric optical properties,
electronic transitions and kinetic stability [39] FMOs of L and complexes 1-3 were calculated
using DFT; BL3YP/LANL2DZ level of theory. As seen in figure 3 for L, HOMOs are located on
chloro-phenyl and piperazine part whereas LUMOs are located over phenyl-seleno moiety. The
HOMO-LUMO energy gap is 0.18191 eV (table 4). Using this HOMO-LUMO energy gap,
chemical descriptors like softness, hardness (η), electronegativity, chemical potential (µ),
electron-affinity and ionization energy for both the synthesized compounds were carried out.
These properties are calculated as follows [40-42]:
‒ (푰 + 푨)
(1) η = (푰 ‒ 푨)
µ =
χ = (푰 + 푨)
(ퟐ)
(ퟑ)
ퟐ
ퟐ
ퟐ
where I and A represent ionization potential and electron affinity of the compound, which are
actually obtained from HOMO and LUMO energies as I = -EHOMO and A = -ELUMO as per Janak
9

theorem [43] and Perdew et al. [44]. A large HOMO-LUMO gap represents a hard molecule
while a small gap indicates a soft or more reactive/less stable molecule.
For complexes 1-3, HOMOs are located over chloro-phenyl and half piperazine ring,
leaving phenyl-seleno-propyl and respective metal chlorides blank, however LUMO are
homogenously spread over phenyl-seleno and respective metal halides in complexes 1 and 2, but
are restricted over mercury chloride and surroundings in complex 3.
Chemical potential ‘µ’ that measures the escaping ability of electrons from an
equilibrium system decreases in the order as L (-0.11478) > 1 (-0.12949) > 2 (-0.12977) > 3
(-0.13998). Similarly the global electrophilicity index (ω), a global reactivity index that is related
to chemical hardness and chemical potential as introduced by Parr et al. [41] represents the
measure of the stabilization in energy achieved when the system acquires an additional electronic
2
charge from the environment and is given by ω =
. The corresponding values for L and
µ /2휂
complexes 1-3 are 0.07237, 0.10652, 0.10970 and 0.14841 eV, respectively. All these parameters
have been calculated for the target compounds using B3LYP/LANL2DZ basis set and are
depicted in table 4.
3.12. Antimicrobial evaluation
The antimicrobial activities of the ligand as well as complexes were evaluated by serial tube
method and their MIC values are summarized in table 5. Chloromphenicol and flucanozole were
used as standard drugs for antibacterial and antifungal activity, respectively. It was observed that
the ligand shows lowest antibacterial as well as antifungal effect. However, upon complexation
with group 12 metal chlorides its antimicrobial action drastically changes. The highest effect was
observed in case of complex 1 which exhibited an MIC of 12 µg/mL against Aspergillus niger
and 32 µg/mL against Staphylococcus aureus followed by complex 2 which exhibited an MIC of
16 µg/mL against Aspergillus niger and 40 µg/mL against Staphylococcus aureus.
4. Conclusion
1-(3-Chlorophenyl)-4-(3-phenylseleno-propyl)piperazine hydrochloride (L) has been synthesized
by reacting ArSe- (generated in situ by borohydride reduction of diphenyl-diselenide) with 1-(3-
chlorophenyl)-4-(3-chloropropyl)piperazine hydrochloride. Formation of L and its complexes is
the first example of novel synthesis where 1-(3-chlorophenyl)-4-(3-chloropropyl)piperazine is
10

used, which results in the formation of Se,N,N-hybrid donor ligands. Its coordination behavior
was examined with Zn, Cd and Hg metal chlorides. Various spectral and analytical data reveal
that heteroditopic ligand L (Se,N,N) ligates solely Se and N in complexes 1-3 adopting bidentate
mode of ligation. Moreover the coordination from selenium atom is also supported by the
downfield shift of signal in 77Se{1H} NMR spectroscopy.
Using DFT-based optimization of structures, the HOMO-LUMO energy gaps and
molecular electrostatic potential (MEP) surface of ligand L and complexes 1-3 were theoretically
calculated at the B3LYP/LANL2DZ level of theory. These complexes adopt distorted tetrahedral
geometry around M(II) ions as revealed by bond angles. Hybrid ligand (L) (Se,N,N) ligates
solely through Se and N in complexes 1-3 adopting bidentate mode of coordination. HOMO-
LUMO energy gap was calculated which allowed the calculation of relative properties like
chemical hardness, chemical inertness, chemical potential, nucleophilicity and electrophillicity
index of the synthesized products. The experimentally obtained IR and NMR results showed a
good correlation with those of the theoretical ones. Ligand L and complexes 1-3 display
significant antibacterial and antifungal activity.
Acknowledgements
The authors are very thankful to IIIM Srinagar and IIT Delhi for 1H, 13C, DEPT 135o 13C,
77Se NMR and elemental analysis. We are also thankful to Department of Chemistry, Dr. H.S.
Gour University, Sagar for IR analysis and SIAF IIT Kanpur for mass analysis.
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14

15

L
1
2
3
Figure 1. Optimized structures of ligand L and complexes 1-3.
16

L
1
2
3
Figure 2. MEP surface of ligand L and complexes 1-3 calculated using DFT; BL3YP/LANL2DZ
basis set.
17

LUMO 1
LUMO L1
HOMO L1
HOMO 1
LUMO 2
LUMO 3
HOMO 2
HOMO 3
Figure 3. HOMO-LUMO surfaces of ligand L and complexes 1-3 simulated using DFT; BL3YP
/ LANL2DZ level of theory.
18

Table 1. Analytical and physical data of L and complexes 1-3.
Ligand/
Compound
Color
Yield (%)
Solubility
ΛM (S cm2 mol-1)
m.p. (C)
L
1
2
3
Cream
White
White
White
85
82
78
80
66
CHCl3, MeOH, EtOH
MeOH, DMSO, DMF
MeOH, EtOH, DMSO
MeOH, EtOH, DMSO
2.95
3.71
3.81
3.45
123
110
118
Table 2. Selected bond lengths of ligand L and complexes 1-3 theoretically calculated at the B3LYP/LANL2DZ.
Ligand L
Complex 1
Complex 2
Complex 3
(C1-Se7)
1.92
1.97
(C1-Se7)
1.94
1.91
(C1-Se7)
1.93
1.92
(C1-Se7)
1.94
1.92
(C8-Se7)
(C8-Se7)
(C8-Se7)
(C8-Se7)
(C8-C9) 1.52
(C9-C10)
(C8-C9) 1.56
(C9-C10)
(C8-C9) 1.58
(C9-C10)
(C8-C9) 1.58
(C9-C10)
1.53
1.46
1.46
1.52
1.46
1.40
1.41
1.38
1.39
1.76
1.08
1.09
1.09
1.59
1.51
1.40
1.46
1.58
1.40
1.35
1.54
1.35
1.76
1.07
1.07
1.07
1.60
1.51
1.46
1.52
1.54
1.48
1.35
1.53
1.35
1.76
1.07
1.06
1.07
1.60
1.51
1.46
1.52
1.54
1.48
1.35
1.35
1.35
1.76
1.07
1.06
1.07
(C10-N11)
(N11-C12)
(C12-C13)
(13C-N14)
(14C-C17)
(C17-C18)
(C20-C21)
(C21-C22)
(C21-Cl23)
(C22-H46)
(C12-35H)
(C9-H32)
(C10-N11)
(N11-C12)
(C12-C16)
(13C-N14)
(14C-C15)
(C17-C18)
(C20-C21)
(C21-C22)
(C21-Cl23)
(C22-H49)
(C12-39H)
(C9-H32)
(C10-N11)
(N11-C12)
(C12-C16)
(13C-N14)
(14C-C15)
(C17-C18)
(C20-C21)
(C21-C22)
(C21-Cl23)
(C22-H48)
(C12-39H)
(C9-H32)
(C10-N11)
(N11-C12)
(C12-C16)
(13C-N14)
(14C-C15)
(C17-C18)
(C20-C21)
(C21-C22)
(C21-Cl23)
(C22-H48)
(C12-39H)
(C9-H32)
(C1-C6) 1.39
(C4-C5) 1.39
(C3-H25)
(C1-C6) 1.54
(Zn24-Cl25)
(Se7-Zn24)
(N11-Zn24)
(C1-C6) 1.53
(Cd49-Cl25)
(Se7-Cd49)
(N11-Cd49)
(C1-C6) 1.53
(Hg47-Cl24)
(Se7-Hg47)
(N11-Hg47)
2.24
2.36
1.94
2.40
2.50
2.09
2.43
2.53
2.11
1.08
1.08
(C2-H24)
19

Table 3. Selected bond angles of ligand L and complexes 1-3 theoretically calculated at the B3LYP/LANL2DZ.
Ligand L
Complex 1
Complex 2
Complex 3
(Se7-C1-C6)
(Se7-C8-C9)
120.20
112.58
(Se7-C1-C6)
(Se7-C8-C9)
119.99
112.90
(Se7-C1-C6)
(Se7-C8-C9)
120.00
113.91
(Se7-C1-C6)
(Se7-C8-C9)
120.00
114.19
(Se7-C8-H30) 107.32
(Se7-C8-H30) 107.50
(Se7-C8-H30) 107.11
(Se7-C8-H30) 106.99
(Se7-C1-C2)
(C2-1C-C6)
(C8-C9-C10)
120.07
119.67
112.16
(Se7-C1-C2)
(C2-1C-C6)
(C8-C9-C10)
120.00
119.99
114.52
(Se7-C1-C2)
(C2-1C-C6)
(C8-C9-C10)
119.98
120.01
116.26
(Se7-C1-C2)
(C2-1C-C6)
(C8-C9-C10)
120
120
116.52
(C9-C10-N11) 113.21
(C10-11N-C12) 113.26
(N11-12C-C13) 110.44
(C12-C13-N14) 110.82
(C13-N14-C15) 111.49
(C13-N14-C17) 117.55
(N14-C17-C18) 120.11
(C18-C17-C22) 117.88
(C19-C20-C21) 117.58
(C20-C21-Cl23) 119.24
(C19-C20-H45) 121.61
(C9-C10-N11) 119.34
(C10-11N-C12) 113.58
(N11-12C-C16) 126.30
(N11-C12-C14) 111.79
(C13-N14-N15) 111.79
(C14-N15-C16) 107.95
(N15-C17-C18) 119.99
(C18-C17-C22) 120
(C9-C10-N11) 119.86
(C10-11N-C12) 114.38
(N11-12C-C16) 116.61
(N11-C13-C14) 109.46
(C12-C16-N15) 108.24
(C14-N15-C16) 111.31
(N15-C17-C18) 119.99
(C18-C17-C22) 119.98
(Se7-Cd49-Cl25) 110.91
(C8-Se7-Cd49) 101.93
(N11-Cd49-Cl25)111.26
(C9-C10-N11) 120.03
(C10-11N-C12) 114.41
(N11-12C-C16) 116.60
(N11-C13-C14) 109.48
(C12-C16-N15) 108.25
(C14-N15-C16) 111.30
(N15-C17-C18) 120
(C18-C17-C22) 120
(Se7-Zn24-Cl25) 111.83
(C8-Se7-Zn24) 101.29
(N11-Zn24-Cl26)110.26
(Se7-Hg47-Cl24) 111.11
(C8-Se7-Hg47) 101.79
(N11-Hg47-Cl24)
111.66
(N11-C12-H36) 111.40
(C10-N11-Zn24) 113.56
(C13-N11-Zn24) 119.67
(C1-Se7-Zn24) 112.87
(C10-N11-Cd49) 114.17
(C13-N11-Cd49) 110.06
(C1-Se7-Cd49) 116.62
(C10-N11-Hg47) 114.06
(C13-N11-Hg47) 110.07
(C1-Se7-Hg47) 113.67
(C2-C1-C6)
119.67
119.84
(C6-C5-H27)
Table 4. Calculated energy values for ligand L and complexes 1-3 using B3LYP/ LANL2DZ basis set.
Parameter
L
1
2
3
Energy (a.u.)
-3706.995
3.2244
-967.024
7.9324
-949.480
8.1830
-944.123
7.7984
Dipole moment (Debye)
EHOMO (eV)
-0.20524
-0.20819
-0.20652
-0.20599
ELUMO (eV)
-0.02333
0.18191
-0.21355
-0.01274
0.20081
0.09095
-0.05079
0.15740
-0.25409
-0.03238
0.22171
0.07870
0.05302
0.15350
-0.25266
-0.03778
0.21488
0.07675
-0.07397
0.13202
-0.25167
-0.05640
0.19527
0.06601
EHOMO-LUMO (eV)
EHOMO-1 (eV)
ELUMO+1 (eV)
E(HOMO-1)-(LUMO+1) (eV)
Hardness (η)
Chemical potential (µ)
Electronegativity (χ)
-0.11478
0.11478
0.07237
-0.12949
0.12949
0.10652
-0.12977
0.12977
0.10970
-0.13998
0.13998
0.14841
Electrophilicity index (ω)
20

Table 5. Antibacterial and antifungal activity (MIC in µg/mL) of ligand L
and complexes 1-3.
Ligand/Compound
Staphylococcus aureus
Aspergillus niger
L
58
32
40
28
< 1
36
12
16
22
1
2
3
Chloromphenicol
Flucanozole
< 1
21