Synthetic stratagem, characterization and biocidal applications of triorganotin(IV) complexes derived from hydrazide/hydrazone analogues

Article abstract of DOI:10.1016/j.ica.2018.10.009

A series of Schiff base ligands as benzylidene benzohydrazide and their hydrazone analogues (I_a-I_c) have been synthesized and then complexed with organotin(IV) moiety having general formula [R’₃SnL] to get the target compo

Full text of DOI:10.1016/j.ica.2018.10.009

Accepted Manuscript
Research paper
Synthetic Stratagem, Characterization and Biocidal applications of Triorgano-
tin(IV) Complexes derived from Hydrazide/Hydrazone Analogues
Mehwish Mehmood, Imtiaz-ud-Din, Muhammad Nawaz Tahir, Ihsan-ul Haq,
Syeda Saniya Zahra
PII:
S0020-1693(18)30594-2
https://doi.org/10.1016/j.ica.2018.10.009
ICA 18555
DOI:
Reference:
Inorganica Chimica Acta
To appear in:
Received Date:
Revised Date:
Accepted Date:
5 May 2018
4 October 2018
4 October 2018
Please cite this article as: M. Mehmood, Imtiaz-ud-Din, M. Nawaz Tahir, I-u. Haq, S.S. Zahra, Synthetic Stratagem,
Characterization and Biocidal applications of Triorganotin(IV) Complexes derived from Hydrazide/Hydrazone
Analogues, Inorganica Chimica Acta (2018), doi: https://doi.org/10.1016/j.ica.2018.10.009
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Synthetic Stratagem, Characterization and Biocidal applications of
Triorganotin(IV) Complexes derived from Hydrazide/Hydrazone Analogues
Mehwish Mehmooda, Imtiaz-ud-Dina*, Muhammad Nawaz Tahirb, Ihsan-ul Haqc, Syeda Saniya
Zahrac
Corresponding Author: drimtiazuddin@yahoo.com
a Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan.
b Department of Physics, University of Sargodha, Sargodha 40100, Pakistan.
c Department of Pharmacy, Quaid-i-Azam University, Islamabad 45320, Pakistan.
Abstract
A series of Schiff base ligands as benzylidene benzohydrazide and their hydrazone analogues
(Ia-Ic) have been synthesized and then complexed with organotin(IV) moiety having general
formula [R'3SnL] to get the target compounds(1-9), where L= C4H3OCONHN=CHR, R=
C6H5O(Ia), C4H5O(Ib), C6H3Cl2(Ic) and R'= -CH3(1-3), -CH2Ph(4-6), -Ph(7-9). They were fully
characterized using FT-IR, NMR(1H, 13C and 119Sn) spectroscopy, along with elemental analysis
and melting point. One of the precursor (Ib) has been analyzed by single crystal XRD to further
authenticate the structure. The 119Sn NMR data suggest the molecular geometry of organotin
derivatives as distorted pentagonal bipyramidal. They were also evaluated for their antibacterial,
antifungal, α-amylase inhibition, DPPH, total reducing power and total antioxidant activities.
Triaryltin(IV) derivatives show good antibacterial and antifungal activity. Whereas the data for
antidiabetic activity demonstrated that the compounds may serve as moderately effective alpha
amylase inhibitor.
Keywords: Organotin(IV), Hydrazone, Spectroscopy, X-ray, Alpha Amylase inhibition.
1) Introduction
Organotin(IV) complexes, derived from Schiff bases, have got tremendous importance because
of their diverse applications in medicinal and non-medicinal fields[1, 2]. Hydrazides and
hydrazones functionalities are considered to be associated with antibacterial[3], antifungal[4],
antiplatelet[5] ,anticancer and anti-inflammatory activities[6]. A large number of Schiff bases
possess some interesting properties and have been applied in various fields such as their catalytic
role in a variety of reactions like hydrogenation, their ability to bind reversibly with oxygen[7]
,as well as studies related to fluorescent, photochromic properties[8] and specifically due to their
complexing and chelating ability towards some metals[9].

The present invoke in organotin chemistry comes up with their insecticidal [10], anti-
inflammatory[11] and antimicrobial [12] activity. In perpetuation to our previous work [13, 14],
we report here the synthesis, spectral studies and variety of biological applications of
benzylidene benzohydrazide ligands (Ia-Ic) and their organotin derivatives (1-9). The bioactivity
of organotin complexes may be affected by the nature and number of donor species, structure as
well as their coordination number[15-22]. The effectiveness was further dictated by the presence
of specific substituents on the triorganotin moiety. The organotin moiety effects the inhibition of
bacterial species due to the attachment of triaryltin moiety, which increases the activity of
complex exhibiting MIC values extremely low in mM as compare to the ligands[15]. The data
suggest that certain compounds could provide a basic scaffold for optimized antibacterial agents
and need to be bioassayed further for discovering potential therapeutic agent in future drug
discovery process[23].
2) Experimental Section
2.1 Materials and methods
2-Furoic acid hydrazide, 3-hydroxybenzaldehyde, furaldehyde, 2,4-dichlorobenzaldehyde,
trimethyltin chloride and triphenyltin chloride were commercially available and were used as
received. Tribenzyltin chloride was prepared as reported earlier[24]. All the solvents used dried
using known procedure[25]. The melting points were determined by electro thermal melting
point apparatus (model MP-D Mitamura Riken Kogyo Japan) and were uncorrected. The IR
spectra were recorded with Bio-Rad Excalibur (model FTS 3000 MX), on KBr discs. The
multinuclear (1H, 13C and 119Sn) NMR spectra were recorded on Bruker Advance Digital 300
MHz FT-NMR spectrometer (Switzerland) in deuterated methanol and DMSO as solvents
relative to Me4Si and Me4Sn as internal reference. The X-ray structure were determined by using
Olex2 [26], the structure was refined with ShelXL-1997 refinement package and solved with the
ShelXT structure solution program.
2.2 Synthesis of Precursor
The precursors (Ia-Ic) as benzylidene benzohydrazide were prepared by reacting stoichiometric
amounts of 2-furoic acid hydrazide and the respective substituted aromatic aldehydes, which
were dissolved in freshly dried ethanol. The reaction mixture was refluxed for 3-4 hours with
constant stirring. The resultant solution was cooled to room temperature with subsequent rotary

evaporation to get the crude product. Recrystallization was carried out in dichloromethane and
petroleum ether mixture(1:3) to yield the purified product [27].
2.2.1 (3-hydroxybenzylidene)furan-2-carbohydrazide (I )
a
Quantities used; 2-furoic acid hydrazide(0.25g,2mmole) and 3-hydroxybenzaldehyde(0.24g,
2mmole). White crystals, Yield: 85% ; Melting point: 208-210 0C; Anal. Calcd. for C10H10N2O3
(230.22): C, 62.60; H, 4.38; N, 12.17%. Found: C, 62.56; H, 4.31; N, 12.19%; FT-IR Data (KBr,
1
cm-1) ν(OH) 3265, ν(NH) 3119, ν(C=O) 1648, ν(C=N) 1589, ν(N-N) 1012, ν(C-O-C) 1288.; H NMR Data
(DMSO, δ, ppm) 11.81(1H, s, OH), 9.65(1H, s, NH), 8.36(1H, s, N=CH), 7.95-6.70(7H, m, Ar-
H); 13C NMR Data (DMSO, δ, ppm) 158.1 (CO=N), 154.6(N=CH), 147.0, 146.3, 113.0,
112.5(furan-C), 148.3, 148.4,135.9, 10.3, 117.9,115.3 (Ar-C).
2.2.2 (furan-3-ylmethylene)furan-2-carbohydrazide (I )
b
Quantities used; 2-furoic acid hydrazide(0.25g, 2mmoles), furaldehyde(0.16mL,2mmole), brown
crystals, Yield: 90% ; Melting point: 192-195 0C; Anal. Calcd. for C10H8N2O3 (204.18): C, 58.82;
H, 3.95; N, 13.72%. Found C, 58.84; H, 3.89; N, 13.74%; FT-IR Data (KBr, cm-1) ν(NH) 3268,
1
ν(C=O) 1649, ν(C=N) 1575, ν(N-N) 1027, ν(C-O-C) 1291; H NMR Data (DMSO, δ, ppm) 11.83(1H, s,
NH), 8.33(1H, s, N=CH), 7.94-6.63(6H, m, Ar-H); 13C NMR Data (DMSO, δ, ppm) 156.8
(CO=N), 149.8(N=CH), 147.0, 146.3, 113.0, 112.5(furan-C), 148.3, 148.4,135.9, 10.3, 117.9,
115.3 (Ar-H).156.8 (CO=N), 149.8 (N=CH), 147.05, 146.28, 145.69, 138.03, 115.48, 114.06,
112.69, 112.60 (furan-C).
2.2.3 (2,4-dichlorobenzylidene)furan-2-carbohydrazide (I )
c
Quantities used; 2-furoic acid hydrazide(0.25g, 2mmoles), 2,4-dichlorobenzaldehyde(0.35g,
2mmole), White product; Yield: 80% ; Anal. Calcd. for C12H8Cl2N2O2 (282): C, 50.91; H, 2.85;
N, 9.89%. Found C, 50.87; H, 2.92; N, 9.86%; Melting point: 135-137 0C; FT-IR Data (KBr, cm-
1) ν(NH) 3267, ν(C=O) 1647, ν(C=N) 1577, ν(N-N) 1014, ν(C-O-C) 1292 ; 1H NMR Data (DMSO, δ, ppm)
11.28(1H, s, NH), 8.87(1H, s, N=CH), 8.15-6.67(6H, m, Ar-H); 13C NMR Data (DMSO, δ, ppm)
156.8 (CO=N), 149.8(N=CH), 145.5, 142.3,115.3, 112.0 (furan-C), 135.6, 134.3, 131.0, 129.3,
128.2, 127.8 (Ar-C).
2.3 Synthesis of targeted compounds (1–9)
Stoichiometric amount of the respective ligands (1mmole) was dissolved in 10mL methanolic
solution of potassium hydroxide (1mmole) and refluxed for an hour to get potassium salt of

hydrazone ligand. Then added the appropriate organotin(IV) chlorides into the above solution.
The mixture was refluxed with constant stirring for 8-10 hours. The clear solution thus obtained
was rotary evaporated to get the targeted compound. They were recrystallized in suitable
solvent[15].
2.3.1 [(3-hydroxybenzylidene)furan-carbohydrazide] Trimethyltin(IV) (1)
Quantities used; (3-hydroxybenzylidene)furan-2-carbohydrazide (0.204g, 1mmole), potassium
hydroxide (0.1g,1mmole), (CH3)3SnCl (0.2g, 1mmole). Dark brown product; Yield: 70% ;
Melting point: 182-185 0C; Anal. Calcd. for C15H18N2O3Sn(393): C, 45.84; H, 4.62; N, 7.13%.
Found C, 45.87; H, 4.53; N, 7.11%; FT-IR Data(KBr, cm-1) ν(OH) 3105, v(NH) 3019, ν(C-O)- 1336,
ν(C=N)1531, ν(N-N) 1015, ν(C-O-C) 1291, ν(Sn-O) 695, ν(Sn-C) 531, ν(Sn-N) 451; 1H NMR Data (MeOD, δ,
ppm) 11.70 (1H, s, OH), 8.30 (1H, s, N=CH). 8.08-6.52 (7H, m, Ar-H), 0.46 (9H, t, JSn-H
=
69Hz, -CH3); 13C NMR Data (MeOD , δ, ppm) 154.5 (CO=N), 145.4 (CH=N), 145.2, 146.6,
134.9, 128.7, 115.3, 113.2 (Ar-C), 145.5, 143.4, 112.6, 111.9 (furan-C); 119Sn NMR
Data(DMSO, δ, ppm) -138.84 ppm.
2.3.2 [(furan-3-ylmethylene)furan-2-carbohydrazide] Trimethyltin(IV) (2)
Quantities used; (furan-3-ylmethylene)furan-2-carbohydrazide (0.204g, 1mmole), KOH (0.1g,
1mmole); (CH3)3SnCl (0.2g, 1mmole). Dark brown; Yield: 63% ; Melting point: 180-1820C;
Anal. Calcd. for C13H16N2O3Sn(367): C, 42.55; H, 4.39; N, 7.62%. Found C, 42.57; H, 4.32; N,
7.59%; FT-IR Data (KBr, cm-1) v(NH) 3106, ν(C-O)- 1336, ν(C=N)1530, ν(N-N) 1014, ν(C-O-C) 1290,
1
ν(Sn-O) 689, ν(Sn-C) 523, ν(Sn-N) 455; H NMR Data(300MHz, MeOD, δ ppm) 8.33 (1H, s, N=CH).
13
7.94-6.63 (6H, m, Ar-H), 0.411 (9H, t, JSn-H = 67Hz, -CH3 ); C NMR Data(δ ppm) 149.8
(CO=N), 147.0 (CH=N), 146.6, 145.6, 138.0, 145.6, 138.0, 115.4, 114.0 (Ar-C).
2.3.3 [(2,4-dichlorobenzylidene)furan-2-carbohydrazide] Trimethyltin(IV) (3)
Quantities used; (2,4-dichlorobenzylidene)furan-2-carbohydrazide (0.17g, 1mmole), KOH
(0.1g,1mmole); (CH3)3SnCl 0.2g(1mmole). White; Yield: 72% ; Melting point: 155-1600C;
Anal. Calcd. for C15H16N2Cl2O2Sn(446): C, 40.40; H, 3.62; N, 6.28%. Found C, 40.38; H, 3.66;
N, 6.25%; FT-IR Data(KBr, cm-1) v(NH) 2921, ν(C-O)- 1373, ν(C=N)1589, ν(N-N) 1008, ν(C-O-C) 1309,
ν(Sn-O) 662, ν(Sn-C) 515, ν(Sn-N) 465; 1H NMR Data(MeOD, δ, ppm) 8.83 (1H, s, N=CH). 8.01-6.70
(6H, m, Ar-H), 0.41 (9H, t, JSn-H = 67Hz, -CH3); 13C NMR Data(MeOD, δ, ppm) 155.0 (CO=N),
146.6 (CH=N), 143.4, 135.5, 134.3, 131.1, 129.8, 128.5 (Ar-C), 146.6, 143.4, 116.4, 112.6
(furan-C).

2.3.4 [(3-hydroxybenzylidene)furan-2-carbohydrazide] Tribenzyltin(IV) (4)
Quantities used; (3-hydroxybenzylidene)furan-2-carbohydrazide (0.204g, 1mmole), potassium
hydroxide (0.1g, 1mmole), (C6H5CH2)3SnCl (0.43g, 1mmole). Dark yellow; Yield: 55%; Melting
point: 113-1150C; Anal. Calcd. for C33H30N2O3Sn(621) : C, 63.79; H, 4.87; N, 4.51%. Found C,
63.78; H, 4.79; N, 4.53%; FT-IR Data(KBr, cm-1) ν(OH) 3268, v(NH) 3078, ν(C-O)- 1339, ν(C=N)1551,
1
ν(N-N) 1054, ν(C-O-C) 1290, ν(Sn-O) 604, ν(Sn-C) 501, ν(Sn-N) 447; H NMR Data(300MHz, MeOD, δ
ppm), 12.23 (1H, s, OH), 8.65 (1H, s, N=CH). 7.94-6.71 (22H, m, Ar-H), 2.467 (6H, t, JSn-H
=
13
69Hz, SnCH2Ph); C NMR Data(δ ppm) 154.2 (CO=N), 147.0 (CH=N), 132.6, 128.3, 128.0,
124.7, 124.2, 121.4 (Ar-C), 143.3, 139.0, 113.4, 112.8(furan-C).
2.3.5 [((furan-3-ylmethylene)furan-2-carbohydrazide] Tribenzyltin(IV) (5)
Quantities used; (furan-3-ylmethylene)furan-2-carbohydrazide (0.204g, 1mmole), KOH (0.1g,
1mmole), (C6H5CH2)3SnCl (0.43g, 1mmole); Brown; Yield: 70%; Melting point: 145-1480C;
Anal. Calcd. for C31H28N2O3Sn(595) : C, 62.55; H, 4.74; N, 4.71%. Found C, 62.59; H, 4.72; N,
4.71%; FT-IR Data (KBr, cm-1) v(NH) 3105, ν(C-O)- 1386, ν(C=N)1588, ν(N-N) 1050, ν(C-O-C) 1291, ν(Sn-
1
592, ν(Sn-C) 548, ν(Sn-N) 450; H NMR Data(MeOD, δ, ppm) 8.25 (1H, s, N=CH). 7.76-6.59
O)
(21H, m, Ar-H), 2.53 (6H, t, JSn-H = 71Hz, -CH3 ); 13C NMR Data(MeOD, δ, ppm) 149.5
(CO=N), 145.7 (CH=N), 145.1, 139.6, 128.0, 113.7, 111.8 (Ar-C), 119Sn NMR Data(DMSO, δ,
ppm) -138.96 ppm.
2.3.5 [(2,4-dichlorobenzylidene)furan-2-carbohydrazide] Tribenzyltin(IV) (6)
Quantities used; (2,4-dichlorobenzylidene)furan-2-carbohydrazide (0.28g, 1mmole), KOH (0.1g,
1mmole); (CH3)3SnCl (0.43g, 1mmole), White; Yield: 75%; Melting point: 120-1250C; Anal.
Calcd. for C33H28Cl2N2O2Sn(674) : C, 58.7; H, 4.19; N, 4.16%. Found C, 58.3; H, 4.13; N,
4.18%; FT-IR Data(KBr, cm-1) v(NH) 3132, ν(C-O)- 1374, ν(C=N)1588, ν
1050, ν(C-O-C) 1291,
(N-N)
ν(Sn-O) 592, ν(Sn-C) 548, ν(Sn-N) 450; 1H NMR Data(MeOD, δ, ppm) 8.79 (1H, s, N=CH). 8.26-6.67
(6H, m, Ar-H), 2.52 (6H, t, JSn-H = 71.4Hz, SnCH2Ph); 13C NMR Data(MeOD, δ, ppm) 145.9
(CO=N), 144.0 (CH=N), 136.4, 129.0, 128.2, 127.6, 127.5, 123.9 (Ar-C), 139.7, 134.7, 116.0,
119.9 (furan-C).
2.3.7 [(3-hydroxybenzylidene)furan-2-carbohydrazide] Triphenyltin(IV) (7)
Quantities used; (3-hydroxybenzylidene)furan-2-carbohydrazide (0.35g, 1.5mmole), potassium
hydroxide (0.2g, 1.5mmole), (C6H5)3SnCl (0.58g, 1.5mmole) were used. Brown; Yield: 60% ;
Melting point: 105-1100C; Anal. Calcd. for C30H24N2O3Sn(579) : C, 62.21; H, 4.18; N, 4.84%.

Found C, 62.24; H, 4.23; N, 4.87%; FT-IR Data(KBr, cm-1) ν(OH) 3268, v(NH) 3044, ν(C-O)- 1330 ,
1
ν(C=N)1578, ν(N-N) 1077, ν(C-O-C) 1261, ν(Sn-O) 661, ν(Sn-C) 454, ν(Sn-N) 445 ; H NMR Data (MeOD,
δ, ppm), 11.80 (1H, s, OH), 8.51 (1H, s, N=CH). 7.82-7.41 (22H, m, Ar-H); 13C NMR
Data(MeOD, δ, ppm) 152.5 (CO=N), 144.5 (CH=N), 136.0, 129.3, 129.2, 129.1, 128.8(Ar-C),
139.6, 136.5, 128.3, 127.2(furan-C).
2.3.8 [((furan-3-ylmethylene)furan-2-carbohydrazide] Triphenyltin(IV) (8)
Quantities used; (furan-3-ylmethylene)furan-2-carbohydrazide (0.30g, 1.5mmole), KOH (0.2g,
1.5mmole); (C6H5)3SnCl (0.58g, 1.5mmole), Brown; Yield: 65% ; Melting point: 125-1280C;
Anal. Calcd. for C28H22N2O3Sn(553): C, 60.79; H, 4.01; N, 5.06%. Found C, 60.75; H, 3.95; N,
5.04%; FT-IR Data(KBr, cm-1) v(NH) 3064, ν(C-O)- 1291 ν(C=N)1587, ν(N-N) 1021, ν(C-O-C) 1291, ν(Sn-
1
690, ν(Sn-C) 526, ν(Sn-N) 462; H NMR Data(MeOD, δ, ppm) 8.25 (1H, s, N=CH), 7.72-6.59
O)
13
(21H, m, Ar-H); C NMR Data(MeOD, δ, ppm) 150.0(CO=N), 149.6 (CH=N), 145.6, 145.1,
139.5, 138.6, 113.7, 115.4(furan-C).
2.3.9 [(2,4-dichlorobenzylidene)furan-2-carbohydrazide] Triphenyltin(IV) (9)
Quantities used; (2,4-dichlorobenzylidene)furan-2-carbohydrazide (0.43g, 1.5mmole), KOH
(0.2g, 1.5mmole), (C6H5)3SnCl (0.30g,1.5mmole), off white; Yield: 55% ; Melting point: 117-
1200C; Anal. Calcd. for C30H22Cl2N2O2Sn(632): C, 57.00; H, 3.51; N, 4.43%. Found C, 56.96;
H, 3.56; N, 4.40%; FT-IR Data(cm-1) v(NH) 3044, ν(C-O)- 1374 ν(C=N)1589, ν(N-N) 1018, ν(C-O-C)
1
1310, ν(Sn-O) 616, ν(Sn-C) 557, ν(Sn-N) 445; H NMR Data(MeOD, δ, ppm) 8.78 (1H, s, N=CH).
8.24-6.66 (21H, m, Ar-H); 13C NMR Data(MeOD, δ, ppm) 156.1 (CO=N), 146.1 (CH=N), 139,4,
136.5, 136.2, 134.7, 129.2, 128.8 (Ar-C), 145.9,144.1, 116.0, 111.9 (furan-C); 119Sn NMR
Data(DMSO, δ, ppm) -127.46 ppm.
2.4 X-rays Crystallography
Single crystal analysis for Ib was carried out, the crystallographic data and structural refinement
details are given in Table 1. During data collection a suitable crystal was selected and kept at
296(2) K. Using Olex2 [26], the structure was resolved with ShelXT structure solution program
and structure refinement was done by using Least Squares minimization with ShelXL-1997
refinement package [28].
Table 1 : Crystallographic data and refinement details for (I )
b
Identification code
Empirical formula
Ib
C10H8N2O3

Formula weight
204.18
3) Results
and
Temperature/K
296(2)
Crystal system
Orthorhombic
Discussion
Space group
Pbca
a/Å
11.2772(13)
3.1 Chemistry
All the ligands
b/Å
7.5345(7)
c/Å
22.812(3)
(Ia-Ic)
were
α/°
90
synthesized
using
β/°
90
γ/°
90
condensation
reaction
Volume/Å3
Z
1938.3(4)
8
ρcalc`g/cm3
1.399
between
μ/mm-1
0.106
aromatic
F(000)
848.0
aldehydes and
Crystal size/mm3
Radiation
0.440 × 0.180 × 0.160
MoKα (λ = 0.71073)
5.08 to 53.996
-14 ≤ h ≤ 14, -9 ≤ k ≤ 5, -29 ≤
l ≤ 29
2-furoic
acid
hydrazide in 1:1
molar ratio to
yield hydrazone
analogues using
2θ range for data collection/°
Index ranges
Reflections collected
15332
Independent reflections
2116 [Rint = 0.0558, Rsigma
0.0445]
=
the
reported
methodology[29
]. The target
compounds (1-
Data/restraints/parameters
Goodness-of-fit on F2
2116/0/136
1.031
Final R indexes [I>=2σ (I)]
Final R indexes [all data]
Largest diff. peak/hole / e Å-3
R1 = 0.0512, wR2 = 0.1234
R1 = 0.0902, wR2 = 0.1468
0.20/-0.26
9)
were
synthesized by
refluxing
methanolic solution of respective hydrazone Schiff base with appropriate triorganotin(IV)
chloride in the presence of potassium hydroxide, in 1:1 molar ratio (scheme 1). These
synthesized products are stable in moist air and were fully characterized using sophisticated
analytical techniques, the details of which are presented in the experimental section.

Scheme 1
3.2 FT-IR Data
The FT-IR data manifested the presence of all the functionalities found in the target compounds
(1-9). Most prominent stretching vibrational band for ν(C=N) was observed around 1588cm-1 in
free ligand that was slightly shifted to lower frequency around 1531cm-1 on coordination with the
metal. Another diagnostic absorption band which aids in determining the binding mode, is the
carbonyl stretch ν(C=O), which appears at 1648cm-1 in free ligand and another band for (C-O)-
which appears around 1336cm-1. The data clearly manifested that this shift to the lower
frequency is due to the coordination of O from carbonyl and N from azomethine moiety with the
respective organotin moiety.
Absorption band for ν(N-N) was observed around 1012 cm-1 in free ligand but upon coordination
with respective organotin moiety a shift of 5-10 cm-1 was observed towards the region of higher

frequency. A band of medium intensity is observed around 1288 cm-1 in ligand for ν(C-O-C) of
furan ring and it almost remains unaltered in organotin derivatives, which clearly indicate non-
involvement of the O belonging to furan ring upon complexation. Metal to ligand vibration
bands for Sn-O and Sn-N were observed in far IR region in range of 410-490 cm-1 and 470-490
cm-1 respectively which provide valid evidence for the formation of complexes.
3.3 1H, 13C and 119Sn NMR data
The structure of the synthesized complexes were ascertained by using multinuclear (1H, 13C and
1
119Sn) NMR spectroscopy. The H NMR data explicitly determine all the magnetically
equivalent protons present in the ligand, as well as in the targeted compounds (1-9). In case of
n
triorganotin(IV) complexes J[Sn-1H] coupling values further assist in determining geometric
shape of the complex[30]. The chemical shift value for N-H proton appear in range 9.65-
11.82ppm belong to hydrazone Schiff base where as it disappeared in the spectra of all the
complexes. It provides evidence that complexation occur through N-H functionality of the
ligand. The non-involvement of –OH proton in complexation can be inferred from the resonance
occurred at about 11.81ppm. All the chemical shift values for furan and phenyl ring protons
appears in their usual regions both for the precursors and targeted compounds. Some additional
satellite peaks were also observed for trimethyltin(IV) derivatives at 0.46(1), 0.41(2),
0.41(3)ppm which refers to 2J [119Sn, 1H].
2
1
The coupling constant J [119Sn, H] for (1) a representative trimethyltin(IV) derivative 1 was
calculated and found to be 69Hz. Whereas θ value is to be 119° by using Lockhart-Manders
equation[31]. The coupling constant 2J [119Sn, 1H] for a representative tribenzyltin(IV) derivative
6 was calculated and found to be 71Hz. Whereas θ value was determined to be 121° and all these
calculated values are well documented that clearly demonstrated that all triorganotin(IV)
derivatives are five coordinated having trigonal bipyramidal as their geometric shape [32, 33].
The 13C NMR data clearly resolved all the unique carbons for (1-9). The two characteristics
resonances pertaining to C=O and –N=CH moieties appear at 165.3 and 154.5 ppm respectively,
these signals are slightly shifted to upfield regions for all the complexes. The aromatic carbons
appear in their usual region. Furthermore characteristic resonances for all the complexes were
also observed and are given in the experimental section.
The 119Sn NMR spectroscopy is another diagnostic tool to determine the geometry and
coordination number of synthesized organotin derivatives. The chemical shift values for 1, 5 and

9 lie in range -90 to -190ppm which is the reference value for five coordinated organotin
compound[34-36]. This data provide evidence that the geometry of all the synthesized
complexes is distorted trigonal bipyramidal[32].
3.4 X-ray Crystallography
ORTEP diagram is delineated in Fig.1. The structural refinement parameters and
crystallographic data for (Ib) are presented in Table 1. The data for selected bond lengths, bond
angles and hydrogen bonding have been given as supplementary information. The data suggest
that eight molecules of (Ib) are enclosed in one unit cell. The bond distance for C(5)- O(2) and
C(6) -N(2) is 1.231(2) and 1.273(2)˚A respectively which is in close agreement with the reported
bond length for double bond[27]. The N(1)- N(3) bond distance is 1.377(2)˚A which is shorter
than the bond distance of single bond that is, 1.411(7)˚A showing some double bond
character[27]. Bond angles for O(2)- C(5)- N(1) and O(2)- C(5)- C(4) are 123.03˚(18) and
120.27˚(18) respectively, exhibiting a planer structure for the molecule.
Figure 1. ORTEP diagram for Ib
3.5 Biological studies
Triorganotin(IV) complexes are potentially bioactive owning to their biocidal properties and are
used as an industrial biocides like fungicides, insecticide and also as a rodent repellent. The
following biological activities were carried out to further explore their bioeffectiveness.
3.5.1 Antibacterial activity
All the synthesized compounds were preliminarily screened for their antibacterial potential. The
compounds 1, 5, 7, 8 and 9 exhibited good zone of inhibitions against P. aeruginosa. whereas 4-
6 were found to exhibit moderate zones (13 mm) of inhibition against B. subtilis, K. pneumoniae
and E. coli and 7-9 specifically displayed 12–17 mm zone of inhibition against B. subtilis and E.
coli in comparison to the positive control. Owing to spatial conformations the triorganotin
compounds gain entry into the cell lines of an organism, thus inhibiting the bacterial growth
considerably. Here zone of inhibition ≥ 13 mm in diameter was considered active and was

further screened for MIC values on ninety six well plate. After incubation of 24hours, the
minimum bactericidal concentration MBC was evaluated only for those compounds that show
clear wells, demonstrating that the compound arrested the bacterial growth within this period of
time. The MBC results demonstrate bacteriostatic nature of the compounds such as 1, 5, 7 and 8
against P. aeruginosa, 4 against resistant S. haemolyticus and 9 against E. coli[37].
Table 2 : Antibacterial Activity dataab for (1-9)
S. aureus
B. subtilis
K.
E. coli
P. aeruginosa Resistant E.
Methicillin
Resistant S.
aureus
R
h
Co
pneumoniae
coli
mp.
No.
MIC
mM
MIC
mM
MIC
mM
MIC
mM
MIC
mM
MIC
mM
MIC
mM
ZOI
ZOI
ZOI
ZOI
ZOI
ZOI
ZOI
Z
(mm)
(µg/m (mm)
L)
(µg/m (mm)
L)
(µg/m (mm)
L)
(µg/m (mm)
L)
(µg/m (mm)
L)
(µg/m (mm)
L)
(µg/m (m
L)
9.33± 0.216
---
---
---
---
---
---
---
---
---
---
---
---
---
---
---
---
--
Ia
Ib
Ic
1
---
---
---
---
---
---
---
---
---
---
---
---
---
---
---
---
---
---
---
---
---
0.58
(50)
7.33± 0.244
0.58 (50)
7.33± 0.177
0.58 (50)
---
---
8.33± 0.244 --
0.58 (50)
13.33 0.177 --
±0.58 (50)
---
---
---
---
---
---
---
8.33± 0.127 9.33± 0.127
0.58 (50) 0.58 (50)
9.33± 0.136 9.33± 0.136
---
---
---
---
--
15.33 0.136 7.33± ---
13.33 0.136
±0.58 (50)
---
1
±
1
±
--
2
---
---
0.58
(50)
0.58
(50)
±0.58 (50)
6.33± ---
0.58
0.58
---
6.33±
0.58
---
---
3
---
---
---
12.33 0.080 12.33 0.080 12.33 0.080 ---
±0.58 (50) ±0.58 (50) ±0.58 (50)
---
---
---
---
---
4
11.33 0.084
±0.58 (50)
0.084
16.33 (50)
±0.58
0.084
12.33 (50)
±0.58
7.33± 0.084 12.33 0.084 12.33 0.084 12.33 0.084
5
1
±
1
±
0.58
(50)
±0.58 (50)
±0.58 (50)
±0.58 (50)
14.33 0.002 13.33 0.074 18.33 0.074
12.33 0.074 12.33 0.074 12.33 0.074
±0.58 (50) ±0.58 (50) ±0.58 (50)
6
7
8
---
---
±0.58
7
±0.58 (50)
±0.58 (50)
(1.85)
---
11.33 0.086 9.33± 0.086 13.33 0.086 ---
±0.58 (50) 0.58 (50) ±0.58 (50)
6.33± ---
0.58
--- ---
--
---
---
14.33 0.003 12.33 0.090 13.33 0.090
1
±
13.33 0.090 10.33 0.090 12.33 0.090
±0.58 (50) ±0.58 (50) ±0.58 (50)
---
---
±0.58
3
±0.58 (50)
±0.58 (50)
(1.85)
15.33 0.002 10.33 0.079 11.33 0.079
1
±
12.33 0.079 10.33 0.079 16.33 0.026
±0.58 (50) ±0.58 (50) ±0.58 (16.6)
9
---
---
±0.58
9
±0.58 (50)
±0.58 (50)
(1.85)
0.000
55
(0.25)
0.000
17
(0.08)
0.000
55
(0.25)
0.000 13.33 0.044 13.33 0.044 10.33 0.044
1
±
cefix 24.33
ime ±0.58
29.33
±0.58
24.33
±0.58
13.33
±0.58
55
±0.58 (20)
±0.58 (20)
±0.58 (20)
(0.25)
a) Values are presented as mean ± standard deviation of triplicate analysis.
b) --- : Indicates bacterial strain is resistant to the compound at >50 µg/ml.
3.5.2 Antifungal activity

All the synthesized compounds were also screened for antifungal activity and the data
manifested moderate zone of inhibition in range 12-20 mm against all the tested strains for 7-9,
whereas 1 and 2 were specifically more active against F. solani in range 15-20 mm. The
compound 7, 8 and 9 exhibited good activity against all the fungal strains as compare to
clotrimazole and their MIC values fall in range 6.25-1.56 μg/ml. The data suggest that the
activity of the compounds are mainly governed by the nature of triorganotin moiety, and play a
pivotal role in inhibiting the growth of the tested organisms. The differential behavior of
compounds in terms of specificity was further determined by varying the substituents attached to
the respective organotin moiety. The fugicidal activity of triphenyltin derivatives was significant
followed by trimethyl and tribenzyltin derivatives [38].
Table : 3 Antifungal Activity dataab for (1-9)
No. of
compound
Mucor sp. MIC
F. solani
MIC
mM
(µg/mL)
---
A. niger
MIC
mM
(µg/mL)
---
A.
fumigatus mM
(µg/mL)
---
MIC
A. flavus
mM
(µg/mL)
---
Ia
Ib
Ic
1
---
---
---
---
---
---
---
---
---
10.33±0.58
8.33±0.58
8.33±0.58
8.33±0.58
9.33±0.58
14.33±0.58
12.33±0.58
9.33±0.58
8.33±0.58
18.33±0.58
20.33±0.58
18.33±0.58
31.33±0.58
---
---
6.33±0.58
7.33±0.58
14.33±0.58
19.33±0.58
8.33±0.58
8.33±0.58
8.33±0.58
8.33±0.58
14.33±0.58
16.33±0.58
15.33±0.58
16.33±0.58
0.244
(50)
0.177
(50)
0.031
(12.5)
0.034
(12.5)
0.112
(50)
0.080
(50)
0.084
(50)
0.074
(50)
0.021
(12.5)
0.009
(6.25)
0.011
(6.25)
0.014
(5)
---
---
---
---
---
---
---
11.33±0.58 0.127
(50)
13.33±0.58 0.017
(6.25)
8.33±0.58
9.33±0.58
---
0.127
(50)
0.136
(50)
---
2
11.33±0.58 0.136
(50)
3
---
---
---
---
4
7.33±0.58
7.33±0.58
7.33±0.58
0.080
(50)
0.084
(50)
0.074
(50)
---
---
7.33±0.58
7.33±0.58
9.33±0.58
0.080
(50)
0.084
(50)
0.074
(50)
5
6.33±0.58
6.33±0.58
0.084
(50)
0.074
(50)
6
7
13.33±0.58 0.0026
(1.56)
14.33±0.58 0.009
(6.25)
13.33±0.58 0.011
(6.25)
15.33±0.58 0.0026
(1.56)
15.33±0.58 0.002
(1.56)
14.33±0.58 0.002
(1.56)
21.33±0.58 0.014
(5)
12.33±0.58 0.0026
(1.56)
13.33±0.58 0.002
(1.56)
12.33±0.58 0.002
(1.56)
22.33±0.58 0.014
(5)
8
9
clotrimazole 29.33±0.58 0.014
(5)
a) Values are presented as mean ± standard deviation of triplicate analysis.
b) --- : Indicates fungal strain is resistant to the compound at >50 µg/ml.
3.5.2 Antidiabetic Activity (alpha amylase inhibition assay)

Alpha amylase inhibition assay was performed to determine antidiabetic activity for (1-9). It may
be inferred from Fig. 2 that moderate biological activity was observed for 7-9 in range 35- 40%
at concentration 0.086, 0.090 and 0.079mM, whereas 4-6 demonstrate 20-25% enzyme
inhibitions at 0.080, 0.084 and 0.074mM as compare to acarbose. The data clearly demonstrated
that the compounds are moderately effective alpha amylase inhibitor, however further research
may be carried out in this domain to arrive at a fruitful conclusion. Inspite of that the antidiabetic
activity for the present regime varied in the following order; triphenyltins > tribenzyltins
>trimethyltins.
Figure 2. α-amylase inhibition assay for (1-9).
3.5.3 Free Radical Scavenging Activity
The DPPH activity data have been depicted in Fig.3 described that almost all the synthesized
ligands and organotin(IV) derivatives show good activity with the exception of triphenyltin
derivatives which exhibit poor activity in comparison to positive control. The compounds 4 and
5 showed highest percentage scavenging activity of 31.63% and 18.44% at concentration of
0.322 and 0.336 mM. It has been argued that tribenzyltin(IV) derivatives, being electron donor in
nature, stabilize DPPH radical more effectively that reduces it to exhibit more scavenging

activity as compare to triphenyltin(IV) derivatives(7-9) which were tested at the concentration of
0.345, 0.361 and 0.316 mM respectively.
Figure 3 % Free radical scavenging activity for compounds (1-9).
3.5.4 Total Antioxidant Activity
The antioxidant mechanism involves electron transfer which is dependent on the structure of
antioxidant agent. The compounds 2, 5 and 6 (which were tested at 0.544, 0.336 and 0.296 mM
concentrations respectively) exhibited the highest antioxidant capacity (with TAC values of
55.70 ± 0.77 and 54.57 ± 1.02 µg AAE/mg respectively). The data suggest that they may find
themselves as promising antioxidant agents in future drug development strategy.
3.5.5 Total Reducing Power Assay
The ferric reducing power assay is yet another method to determine the reducing power of the
synthesized compounds involving conversion of potassium ferricyanide to potassium
ferrocyanide that gives intense blue colored complex[39]. The compounds 2, 5 and 6
demonstrated highest reducing potential with TRP values of 387.42 ± 0.75, 307.97 ± 0.79 and

321.89 ± 0.83 µg AAE/mg respectively at 0.544, 0.336 and 0.296 mM. whereas Ib exhibit TRP
value of 183.98±1.25µg AAE/mg at 0.980 mM concentration.
Figure 4: Total antioxidant capacity and total reducing power for (1-9).
3.5.6 Cytotoxicity (brineshrimp lethality assay)
The brine shrimp lethality assay is a simple, robust and inexpensive method for the assessment of
toxicity of any natural or synthetic product. High lethality with LC50 ˂ 100 µg/ml has been
measured by brineshrimp lethality assay that may be categorized as toxic. Highest toxicity with
LC50 ˂ 30 µg/ml has been assigned to 2, 3, 4 and 8 whereas 3 showed LC50 value of 19.76 µg/ml
at concentration of 0.448mM and 8 show LC50 value of 16.62 µg/ml at a low concentration of
0.316mM demonstrated even more toxic. The data suggest that the synthesized organotin(IV)
derivatives are more toxic owing to inherited toxicity of these organomettalics, whereas some
modifications are needed to develop a compromise between the toxicity and activity of such kind
of compounds for future drug discovery processes.

Figure 5 Brine shrimp lethality assay for (1-9).
4) Conclusions
Three new hydrazone Schiff bases (Ia-Ib) and their organotin(IV) derivatives (1-9) were
13
successfully synthesized and well characterized by using FT-IR, multinuclear (1H, C, 119Sn)
NMR spectroscopy and single crystal X-ray diffraction analysis. All the synthesized compounds
were also evaluated to check their biological significance for development of limited structure-
activity relationship and some generalization has been drawn. The data suggest that tribenzyl
and triphenyltin derivatives exhibit good antibacterial and antifungal activity whereas
compounds 2, 5 and 6 show excellent results vis-a-vis total reducing power assay.
Acknowledgements
The authors are thankful to HEC, and QAU, Islamabad, Pakistan, for providing financial
assistance to carry out the research work.
Appendix A. Supplementary data
The CCDC for the reported compound was 1837071. It can be free download from CCDC data
base.
These
data
can
be
obtained
free
of
charge
via

http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
Abbreviations
DPPH : 2, 2-Diphenyl-1-picrylhydrazyl, FRSA: Free radical scavenging activity, IC50 : 50%
Inhibitory concentration, TAC: Total antioxidant capacity, TRP: Total reducing power, DMSO :
Dimethyl sulfoxide, AAE : Ascorbic acid equivalent, MIC : Minimum inhibitory concentration,
MBC : Minimum bactericidal concentration.
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 Some new substituted hydrazones have been synthesized as precursors.
 These precursors then complexed with various triorganotin compounds to further explore
their structural as well as biological aspects.
 All these compounds were fully characterized by advanced analytical techniques for their
structural validation.
 All these compounds were preliminary screened to evaluate their various bioactivities
and found some encouraging results.
Synthetic Stratagem, Characterization and Biocidal applications of
Triorganotin(IV) Complexes derived from Hydrazide/Hydrazone Analogues
Mehwish Mehmooda, Imtiaz-ud-Dina*, Muhammad Nawaz Tahirb, Ihsan-ul Haqc, Syeda Sania
Zahrac
Graphical Abstract: Synopsis
A series of new triorganotin(IV) complexes of Schiff base ligands as benzylidene
benzohydrazide and their hydrazone analogues have been synthesized. Then they were
complexed with organotin(IV) moiety with general formula [R'3SnL] where L= C4H3O-CONH-
N=CH-R, R= C6H5O(Ia), C4H5O(Ib), C6H3Cl2(Ic) and R'= -CH3(1-3), -CH2Ph(4-6), -Ph(7-9). The
complexes (1-9) have been fully characterized by IR, NMR(1H, 13C and 119Sn) spectroscopy,
combined with CHN and melting point determinations.