Pyrazine-based donor tectons: Synthesis, self-assembly and characterization

Article abstract of DOI:10.1039/c5ra21484j

Two new supramolecular building blocks derived from pyrazine are introduced. These molecules, having pendant pyridine units covalently linked to central pyrazine ring, are structurally rigid with pre-defined bite angles. Therefore they can act as donor tectons in design of supramolecular hexagons using coordination driven self-assembly protocol. Multinuclear NMR (including ¹H DOSY) and mass spectrometry have been utilized to confirm the purity and stoichiometry of these self assembled hexagonal ensembles. PM6 molecular modeling studies corroborate their hexagonal shape and nanoscalar dimensions.

Full text of DOI:10.1039/c5ra21484j

View Article Online
View Journal
RSC Advances
This article can be cited before page numbers have been issued, to do this please use: S. Bhowmick, S.
Chakraborty, S. R. Marri, J. N. Behera and N. Das, RSC Adv., 2016, DOI: 10.1039/C5RA21484J.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. This Accepted Manuscript will be replaced by the edited,
formatted and paginated article as soon as this is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/advances

Page 1 of 17
RSC Advances
View Article Online
DOI: 10.1039/C5RA21484J
PyrazineꢀBased Donor Tectons: Synthesis, SelfꢀAssembly and Characterization
Sourav Bhowmick,1 Sourav Chakraborty,1 Subba R. Marri,2 J. N. Behera2 and Neeladri Das1*
1Department of Chemistry, Indian Institute of Technology Patna, Bihar, India
2School of Chemical Sciences, National Institute of Science Education and Research (NISER),
Bhubaneswar 751005, India
Abstract
Two new supramolecular building blocks derived from pyrazine are introduced. These
molecules, having pendant pyridine units covalently linked to central pyrazine ring, are
structurally rigid with preꢀdefined bite angles. Therefore they can act as donor tectons in design
of supramolecular hexagons using coordination driven selfꢀassembly protocol. Multinuclear
NMR (including 1H DOSY) and mass spectrometry have been utilized to confirm the purity and
stoichiometry of these self assembled hexagonal ensembles. PM6 molecular modeling studies
corroborate their hexagonal shape and nanoscalar dimensions.
Introduction
Supramolecular chemistry utilizes nonꢀcovalent interactions for design of complex
architectures.1 These complex frameworks often utilize several multidentate ligands of two or
more types as that bind with each other using nonꢀcovalent interactions. Coordination driven self
assembly of finite supramolecular architectures has emerged as a popular field of research in
modern supramolecular chemistry.1 Among others, one important feature of this synthetic
protocol is the yield of finite two and three dimensional frameworks in a single step reaction.2
This methodology however necessitates design of new building blocks (tectons) for construction
of supramolecular architectures.3,1a,b,k,l In this context, two types of supramolecular building
blocks are utilized, namely donor and acceptor ligands.4,5 While Pd(II) and Pt(II) based inorganic
or organometallic complexes are most popular acceptor tectons, donor tectons are predominantly
organic molecules that contain two or more pyridine units as pendant functional groups.5,6 In the
context of two dimensional metallamacrocycles, polygonal frameworks of various shapes and
sizes have been designed over the past two decades.7,1a,b Interestingly, there are less literature
reports of higher polygons (pentagons, hexagons, etc.) than smaller ones (such as molecular
rhomboids, triangles, rectangles and squares).8 This is because, design of higher polygons
generally requires selfꢀassembly of a relatively larger number of donor and acceptor building
blocks in comparison to the selfꢀassembly event of smaller polygonal macrocycles. Therefore
synthesis of higher polygons (pentagons, hexagons, etc.) is more complex and challenging than
relatively smaller polygons such as square, rhomboid or triangles.
More recently, we have reported in literature a new acceptor tecton derived from pyrazine.9 This
pyrazine based ditopic organometallic complex contains platinum ethynyl motifs. Continuing our
research interest to enrich the existing literature with new tectons and their application in self
assembly of supramolecular frameworks, herein we describe synthesis and characterization of
two new ditopic pyrazine based donor tectons that contain two pyridyl rings covalently
connected to a central pyrazine ring. These donor tectons are interesting because they contain
several N centers (in pyridine or pyrazine rings) that can potentially coordinate with metal
centers. Therefore, these ligands qualify to act as donor building blocks in the self assembly of
finite metallamacrocycles. To illustrate this point, synthesis and self assembly of two new

RSC Advances
Page 2 of 17
View Article Online
DOI: 10.1039/C5RA21484J
platinum(II)ꢀbased molecular polygons is reported herein. These metallamacrocycles were
characterized by multinuclear NMR spectroscopy including 1H DOSY, ESIꢀTOF mass
spectrometry and elemental analyses techniques. Further insight into the shape and size of these
hexagonal macrocycles was obtained by employing molecular simulation using PM6
semiempirical molecular orbital method. Our studies suggest that the resulting
metallamacrocycles are in nanoscalar dimensions.
Result and Discussion
Synthesis and characterization of the pyrazine based organic donor linker 1 and 2.
Using 2,6ꢀdichloropyrazine as a synthon, synthesis of two new pyrazine based donor linkers (1
and 2) were achieved in two steps (Scheme 1). Sonogashira cross coupling reaction of 2,6ꢀ
dichloropyrazine with (trimethylsilyl)acetylene, followed by deprotection of trimethylsilyl group
yielded 2,6ꢀdiethynylpyrazine. Subsequent coupling of 4ꢀ or 3ꢀiodopyridine with 2,6ꢀ
diethynylpyrazine in presence of Pd(0) catalyst and CuI coꢀcatalyst resulted in the formation of
desired organic linkers 1 and 2 respectively in reasonably high yields (> 80%). Both ligands 1
and 2, obtained as white solids, are stable in air/moisture and have high solubility in common
organic solvents. These molecules were fully characterized by FTꢀIR and NMR (1H and 13C)
spectroscopy, mass spectrometry and elemental analyses. In FTꢀIR spectra of 1 and 2, the
presence of a strong band at 2111 cmꢀ1 and 2217 cmꢀ1 (ν C≡C str.) respectively, indicates the
1
presence of ethynyl moiety in final products. In H NMR spectra of 1 and 2 (supporting
information S2 and S3), presence of sharp singlet at 8.75 ppm and 8.86 ppm respectively, were
assigned to the aromatic protons of the pyrazine ring present in these molecules. In the 1H NMR
spectrum of 1, the two sets of signals in the range of 8.69 to 8.68 ppm and 7.48 to 7.47 ppm are
attributed to the pyridyl protons in the product. In case of 2, as expected additional four sets of
1
signal were observed in the H NMR due to the four different kind of chemically inequivalent
protons and this suggests the formation of 2. The 13C{1H} NMR spectrum of both 1 and 2
exhibited all the characteristic peaks corresponds to pyrazine, pyridine and ethynyl units in
expected region (supporting information S2 and S3). In addition, the molecular structure of 1
was further confirmed unambiguously by single crystal Xꢀray analysis.
Scheme 1. Synthesis of pyrazine based organic donor linkers 1 and 2.
Xꢀray crystallography analysis of ligand 1.
Single crystals of 1 was obtained by slow vapor diffusion of acetone into a chloroform solution
of ligand 1 at ambient temperature. Compound 1 was crystallized in a monoclinic system with

Page 3 of 17
RSC Advances
View Article Online
DOI: 10.1039/C5RA21484J
C2/c space group. The asymmetric unit of compound 1 is shown in Figure 1. XꢀRay
crystallographic analysis of ligand 1 indicated presence of various C─H···N short interactions in
its crystal lattice (supporting information S17).
Figure 1: ORTEP diagram for compound 1 with 50% thermal ellipsoid probability.
Improved synthesis and characterization of the linear organometallic acceptor 3 and 4.
There are few reports in the literature wherein Pd(II)/Pt(II) containing symmetrical and ditopic
ligands have been prepared and subsequently utilized as linear (180°) acceptor tectons in the self
assembly of supramolecular polygonal ensembles. Ligands 3 and 4 are examples of such kind of
linear diplatinum ditopic acceptor tectons, first reported by Mukherjee and coꢀworkers.4b,6g Using
anhydrous diethylamine as base, stirring the reaction mixture for 36 hours, and purification of
crude product using column chromatography, compounds 3 and 4 were obtained in 36 and 42 %
yields. In this context, we report herein improved synthesis of 3 and 4, wherein our synthetic
protocol requires lesser reaction time. Moreover the yields of the reaction are considerably
higher than that reported previously. In the improved synthesis being reported herein, transꢀ
PtI2(PEt3)2 was reacted with the respective terminal dialkynes in presence of CuI (catalyst), and
triethylamine (base) in toluene (solvent) at room temperature for 16h (Scheme 2). The yield of
reaction in either case was above 60%. The binuclear linear organometallic acceptors (3 and 4)
were characterized by 1H , 31P NMR and 13C NMR spectroscopy (supporting information S4, S5
31
and S6). The diplatinum acceptors (3 and 4), in their respective P NMR spectrum, exhibited a
singlet at δ = 8.41 ppm and 8.50 ppm with accompanying 195Pt satellites (1JPPt = 1164 Hz and
1
1JPPt = 1163 Hz). The H NMR spectrum of compound (3) exhibited a sharp singlet at δ = 7.14
ppm corresponding to the phenyl protons in the aromatic region, in addition to the other expected
signals due to the ethyl group of PEt3 group. As expected, in the 1H NMR spectrum of compound
4, two sets of signal in the range of 7.46 to 7.31ppm were observed and these correspond to the
phenyl protons in the aromatic region.

RSC Advances
Page 4 of 17
View Article Online
DOI: 10.1039/C5RA21484J
PEt3
Pt
PEt3
trans-Pt(PEt3)2I2
H
TMS
Br
Br
X
X
I
X
Pt
I
CuI,NEt3,Toluene
r.t.,16h
1. Pd(PPh3)4,CuI
THF, r.t, 16h
2. KOH, MeOH
PEt3
PEt3
3 or 4
3, X
=
4, X =
Scheme 2. Synthesis of organometallic acceptor linkers 3 and 4.
Design strategies towards self assembly of supramolecular hexagons.
As per the “directional bonding approach”, two strategies are reported in literature for the
synthesis of convex hexagonal discrete supramolecular ensembles (Chart 1). In the first method,
six ditopic angular tectons (bearing 120° angles between the two binding sites) react with six
complimentary linear tecton (bearing 180° angles between the two binding sites) to yield [6 + 6]
molecular hexagons (Chart 1a).10 In the second method, three donor ditopic 120° units react with
three acceptor ditopic 120° units to yield [3 + 3] molecular hexagons (Chart 1b).11 Herein, we
propose a third strategy that also yields molecular hexagons albeit involving lesser number of
selfꢀassembling units. Unlike the previously reported self assembled molecular hexagons where
the individual tectons occupy a single vertex or edge, in the third strategy, the tecton is designed
in such a way so that it simultaneously occupies two vertices defining the polygon upon self
assembly (Chart 1c).12 The hexagon depicted in Chart 1c may be described as a [2+2] molecular
hexagon. In case of the “hexameric” and “trimeric” hexagonal frameworks (1a and 1b in Chart
1), the resulting polygons are regular hexagons that are equiangular having equilateral edges.
However, the “dimeric” hexagon (Chart 1c) is isogonal (equal angles) but it may not be
equilateral. Ligand 2 is an example of such a ditopic donor tecton that upon self assembly with
an appropriate complimentary linear (180°) acceptor tecton would yield a dimeric ensemble that
is anticipated to have a irregular hexagonal shape.
Chart 1. Schematic representation of (a) [6 + 6] (b) [3 + 3] and (c) [2 + 2] hexagon.
Application of 1 and 2 as tectons in self assembly of supramolecular hexagons.

Page 5 of 17
RSC Advances
View Article Online
DOI: 10.1039/C5RA21484J
To illustrate this point, self assembly and characterization of four cationic hexagons employing
two different synthetic strategies have been described herein (Scheme 3). 1 and 2 are ditopic
donor tectons since these have two pendant pyridine moieties. In ligand 1, the two pyridyl groups
are oriented in such a manner so that this molecule has 120° directionality. On the other hand, in
ligand 2 the two pyridyl donor sites are oriented such that the resulting coordination vectors are
parallel with respect to each other and pointing in the same direction. Thus 1 is an angular donor
tecton while 2 can be described as a donor “molecular clip”. According to the “directionalꢀ
bonding” approach, it is anticipated that the self assembly of 1 with suitable linear ditopic
acceptor linker in an equimolar stoichiometric ratio will yield a [6+6] hexagonal
metallamacrocycle, whereas in case of linker 2, a similar reaction with a 180° linear ditopic
donor tecton would result in the self assembly of a [2+2] discrete ensemble also having a
hexagonal shape.
12+
N
I
Et3P Pt PEt3
N
AgNO3
12NO3
X
+
1
MeOH/CHCl3
N
N
Et3P Pt PEt3
I
[6+6] Selfꢀassembly
3 or 4
1 + 3 = 5
1 + 4 = 6
4+
N
I
Et3P Pt PEt3
N
AgNO3
X
4NO3
+
2
MeOH/CHCl3
[2+2] Selfꢀassembly
N
N
Et3P Pt PEt3
I
3 or 4
2 + 3 = 7
+
=
8
2
4
,
3 X =
4, X =
Scheme 3. Self assembly of [6 + 6] macrocycles (5 and 6) and [2 + 2] macrocycles (7 and 8)
using the pyrazine based organic donor linkers (1 and 2) and organometallic PtII ꢀlinear acceptor
2
tectons (3 and 4).
The 120º donor linker 1 was treated separately with two different linear PtII organoplatinum
2
acceptor complexes 3 and 4. Iodide units (attached to the platinum center) of acceptor complexes
(3 and 4) were abstracted via salt metathesis reaction with 2 equiv. silver nitrate (in chloroform)
and subsequently reacted with methanolic solution of donor linker 1 in 1:1 stoichiometric ratio.
This resulted into the self assembly of corresponding macrocycles 5 and 6 in high yields.
Solubility tests revealed that these self assembled products had high solubility in green solvents
like methanol and ethanol but poor solubility in halogenated solvents such as chloroform and

RSC Advances
Page 6 of 17
View Article Online
DOI: 10.1039/C5RA21484J
dichloromethane. 5 and 6 were completely characterized by multinuclear NMR spectroscopy,
ESIꢀMS spectrometry and elemental analyses. The 31P{1H} NMR spectra of these products (5
and 6) exhibited sharp singlet [15.57 ppm and 15.61 ppm] along with an accompanying pair of
1
platinum satellites [(1JPPt = 1157 Hz and JPPt = 1160 Hz]. This clearly suggested the formation
of a highly symmetrical architecture in each case, wherein all phosphorous nuclei are chemically
equivalent in the product. Additionally, a significant decrease in the magnitude of coupling
constant of concomitant Ptꢀsatellites in the product (5 and 6) relative to the precursor
organoplatinum complexes (3 and 4) was indicative of new metalꢀligand coordination at
1
platinum centers. Similarly, the H NMR spectra of 5 and 6 also suggested the incorporation of
1
both 1 and 3/4 in the respective final products. In the H NMR spectrum of 5 (Figure 2), the
sharp singlet at 8.88 ppm is due to the aromatic protons of pyrazine, whereas the two sets of
signal at 8.83 to 8.79 ppm and 7.83 ppm to 7.82 ppm correspond to the pyridyl protons. The
aromatic proton of PtII acceptor unit appears as sharp singlet at 7.08 ppm. The peaks in the
2
range 1.08 to 1.81 ppm are due to the PEt3 groups attached to the Pt(II)ꢀcenters.
Figure 2. (a) 31P{1H} NMR and (b) 1H NMR spectra of macrocycle 5 recorded in CD3OD.
Similarly in case of 6, all proton signals are assigned precisely. In both cases (5 and 6), the
integration of peaks due to the pyrazine donor unit (1) and PtII acceptor units suggested their self
2
assembly in 1:1 stoichiometric ratio. Therefore, multinuclear NMR (1H, 13C and 31P) spectra of 5
and 6 (supporting information S7, S8 and S9) hinted at the formation of discrete supramolecular
assemblies. Furthermore, the purity of both products (5 and 6) was checked by 1H DOSY NMR
spectroscopy, wherein a single trace in the DOSY NMR (supporting information S13), ratified
the formation of a single product and simultaneously disapproves the possibility of presence of
other macrocycles or oligomers as byproduct. The mass spectrometric analysis (ESIꢀTOFꢀMS) of
5 and 6 also confirmed that reaction of pyrazine donor linker 2 and the PtII acceptor units (3 or
2
4) indeed resulted in the self assembly of desired [6+6] molecular ensembles over other
oligomeric/polymeric products (supporting information S15). The ESIꢀTOFꢀMS spectrum of 5
showed signals due the consecutive loss of nitrate counter anions from expected [6+6]
macrocycle at m/z = 2026.59 [5ꢀ4NO3]4+, 1330.40 [5ꢀ6NO3]6+, 982.30 [5ꢀ8NO3]8+, 866.27 [5ꢀ
9NO3]9+, 773.44 [5ꢀ10NO3]10+ and 634.20 [5ꢀ12NO3]12+. Similarly, in case of 6, the observed
charge states at 2140.64 [6ꢀ4NO3]4+, 1406.43 [6ꢀ6NO3]6+, 1196.65 [6ꢀ7NO3]7+, 1039.32 [6ꢀ

Page 7 of 17
RSC Advances
View Article Online
DOI: 10.1039/C5RA21484J
8NO3]8+, 916.95 [6ꢀ9NO3]9+, 819.06 [6ꢀ10NO3]10+, 738.96 [6ꢀ11NO3]11+ and 672.22 [6ꢀ
12NO3]12+ in ESIꢀTOFꢀMS spectrum confirms the formation of [6+6] macrocyclic architecture.
Both the linkers (1 and 2) contain a pyrazine moiety in the core and are connected with two
peripheral pyridine motifs. However, unlike the former (1), in case of the latter (2) the 0º bite
angle between two nitrogen donor sites of pyridine moiety renders it as a “clip” donor tecton.
The self assembly of linker 2 with linear PtII2 ditopic acceptor complexes (3 and 4) proceeds in a
similar manner as described for linker 1, with the formation of corresponding self assembled
1
13
products (7 and 8). The H, C and 31P{1H} NMR spectra of assemblies 7 and 8 (supporting
information S10, S11 and S12) suggested the incorporation of both the molecular subunits
(pyrazine based organic donor 2 and PtII acceptor unit: 3 or 4). The formation of highly
2
31
symmetrical products was also evident from the sharp P singlet at 15.53 ppm and 15.56 ppm
1
with concomitant platinum satellites (1JPPt = 1156 Hz and JPPt = 1159 Hz) for 7 and 8
1
respectively. Moreover, H DOSY NMR spectra of 7 and 8 also supported the formation of
single species in these self assembly reactions (supporting information S14). These self
assembled products (7 and 8) were also analyzed using ESIꢀTOFꢀMS to identify the number of
each unit (donor/acceptor) present (supporting information S16). The ESIꢀTOFꢀMS analysis of 7
confirmed the formation of a self assembled product with M2L2 stoichiometry [M = PtII
2
acceptors 3 or 4, L = linker 2] with the appearance of charge state at m/z = 2722.84 [7ꢀNO3]+,
1330.42 [7ꢀ2NO3]2+, 866.28 [7ꢀ3NO3]3+ and 634.21 [7ꢀ4NO3]4+ (Figure 3 and supporting
information S16). Similarly for 8, mass signals corresponding to [8ꢀ2NO3]2+ at m/z = 1406.43,
[8ꢀ3NO3]3+ at m/z = 916.95 and [8ꢀ4NO3]4+ at m/z = 672.22 clearly suggests the self assembly of
a [2+2] macrocyclic ensembles (supporting information S16). The peaks corresponding to
species [6ꢀ11NO3]11+, [7ꢀNO3]+, [7ꢀ3NO3]3+ and [8ꢀ3NO3]3+ peaks were isotopically resolved and
were found to match well with the theoretically predicted distribution (Figure 3 and supporting
information S15 and S16).
Figure 3. Experimental (top) and theoretical (bottom) ESIꢀmass spectrum of the macrocycle 7.

RSC Advances
Page 8 of 17
View Article Online
DOI: 10.1039/C5RA21484J
PM6 Molecular modeling of self assembled ensembles 5−8.
Our unsuccessful attempts to structurally characterize these newly synthesized molecular
hexagons (by single crystal Xꢀray diffraction studies) prompted us to employ PM6 semiempirical
molecular orbital method to obtain useful information regarding the shape and size of the
macrocycle and cavity within it. The presence of hexagonal cavity in these macrocycle is clearly
evident from the space filling molecular models of the energyꢀminimized structures of
macrocycles 5ꢀ8. Thus molecular modelling supports the formation of hexagonal shape as
predicted considering the tenets of directional bonding approach (Chart 1). In case of
macrocycles 7 and 8, the [2+2] self assembly of pyrazine based donor 2 and a linear acceptor (3
or 4) results in the formation of an irregular molecular hexagon (Figure 4) which is isogonal but
not equilateral (all edges are not equal in length). In these wellꢀdefined hexagonal
supramolecular macrocycles (7 and 8), two edges are relatively longer (1.87 nm for 7, and 2.3
nm for 8), whereas the other four edges are relatively shorter (0.67 nm for both 7 and 8). On the
other hand, the [6+6] self assembled ensembles (5 and 6) are regular hexagons (Figure 5) in
which each side is of equal length (3.23 nm for 5 and 3.66 for 6). The distance between two
diagonally opposite endocyclic nitrogen atoms is estimated to be 2.19 nm and 2.62 nm
respectively for macrocycle 7 and 8, while in case of [6+6] molecular hexagons 5 and 6 the
distance is relatively larger and found to be 6.19 nm and 7.05 nm respectively. The average
distance between two furthest platinum centers of macrocycles 5ꢀ8 are found to be 1.76 nm, 2.07
nm, 5.76 nm and 6.49 nm respectively.
Figure 4. Simulated space filling molecular model of (a) macrocycle 7 and (b) macrocycle 8
optimized by PM6 semiempirical molecular orbital methods (light gray: C, green: Pt, blue: N).
(Phosphine ligands and H atoms are omitted for clarity).

Page 9 of 17
RSC Advances
View Article Online
DOI: 10.1039/C5RA21484J
Figure 5. Simulated space filling molecular model of (a) macrocycle 5 and (b) macrocycle 6
optimized by PM6 semiempirical molecular orbital methods (light gray: C, green: Pt, blue: N).
(Phosphine ligands and H atoms are omitted for clarity).
In conclusion, we report herein syntheses of two new molecules (1 and 2) in which a central
pyrazine ring is covalently linked to a pyridine unit on either site via ethynyl bridges. The
presence of two pendent pyridine units in 1 and 2 qualifies them to act as donor tectons in
coordination driven self assembly reactions. In conjugation with linear acceptor tectons (3 and
4), self assembly of discrete hexagonal metallamacrocycles (5ꢀ8) have been conveniently
achieved. Although all macrocycles obtained have a hexagonal cavity, as suggested by their
respective PM6 molecular modeling, 5 and 6 are regular hexagons while 7 and 8 have irregular
hexagonal shape.
Experimental Section
General details
All chemicals and anhydrous solvents used in this work were purchased from commercial
sources and used without further purification. 2,6ꢀdiethynyl pyrazine was prepared by following
the reported literature procedures.13 FTIR spectra were recorded in a PerkinElmer Spectrum 400
1
FTꢀIR spectrophotometer. H NMR spectra and 31P NMR spectra were recorded on Bruker
400/500 MHz spectrometers. Elemental analyses were carried out using a Thermo Scientific
Flash 2000 Organic Elemental Analyzer. ESIꢀMS spectra of the compounds were recorded using
a Bruker UltrafleXtreme™ ESI mass spectrometer. DOSY NMR measurements were performed
on a Bruker AV 500 NMR spectrometer using a 5 mm gradient probe at 298 K. DOSY spectra
were recorded using a standard Bruker pulse sequence (ledbpgp2s) with longitudinal eddy
current delay.
General procedure for the synthesis of organic molecules 1 and 2.

RSC Advances
Page 10 of 17
View Article Online
DOI: 10.1039/C5RA21484J
2,6ꢀdiethynylpyrazine (100 mg, 0.78 mmol), 4ꢀiodopyridine (320 mg, 1.561 mmol), CuI (15 mg,
0.078 mmol) and bis(triphenylphosphine)palladium(II) dichloride (55 mg, 0.078 mmol) were
charged in a 50 ml Schlenk flask in the glove box. Subsequently, 20 ml dry THF and freshly
distilled triethylamine (0.5 ml, 3.122 mmol) were added under nitrogen. The reaction mixture
was stirred overnight at room temperature. After overnight stirring, the dark brown reaction
mixture was filtered through a bed of celite. The filtrate obtained was evaporated to dryness on a
rotary evaporator to get crude product which was purified by column chromatography on silica
gel by eluting with 35% ethyl acetate in hexane to isolate the desired product (1 and 2) as off
white solid.
1
Organic linker (1). Yield: 0.192 g, 87%; mp 185ꢀ190 ºC; H NMR (400 MHz, CDCl3): δ 8.75
(s, 2H, ArꢀH), 8.69 (dd, J = 1.52 Hz, 1.52 Hz, 4H, ArꢀH), 7.48 (dd, J = 1.56 Hz, 1.56 Hz, 4H,
ArꢀH). 13C{1H} NMR (CDCl3, 100 MHz): δ 150.0, 146.4, 138.9, 129.3, 125.7, 90.4, 88.1. IR
(ATR): 3015, 2925, 2859, 2223, 1593, 1510, 1403, 1304, 1166, 1010, 894, 820 cmꢀ1. Anal.
Calcd. For C18H10N4 : C, 76.58; H, 3.57; N, 19.85. Found: C, 76.84; H, 3.76; N, 19.97.
1
Organic linker (2). Yield: 0.2 g, 91%; mp 145ꢀ150 ºC; H NMR (400 MHz, CDCl3): δ 8.86 (s,
2H, ArꢀH), 8.72 (s, 2H, ArꢀH), 8.65 (dd, J = 1.48 Hz, 1.48 Hz, 2H, ArꢀH). 7.93ꢀ7.90 (m, 2H, Arꢀ
13
H), 7.37ꢀ7.33 (m, 2H, ArꢀH). C{1H} NMR (CDCl3, 100 MHz): δ 152.7, 149.9, 145.9, 139.2,
123.2, 118.5, 90.1, 88.3. IR (ATR): 3031, 2924, 2856, 2217, 1559, 1510, 1477, 1420, 1304,
1149, 1123, 1001, 811 cmꢀ1. Anal. Calcd. For C18H10N4 : C, 76.58; H, 3.57; N, 19.85. Found: C,
76.88; H, 3.72; N, 19.93.
General procedure for the synthesis of organometallic complexes 3 and 4.
1,4ꢀDiethynylarene (0.238 mmol) and transꢀ(PEt3)2PtI2 (490 mg, 0.714 mmol) were charged in a
25 mL Schlenk flask inside a glovebox. Subsequently, 10 mL of dry toluene and 5 mL of freshly
distilled triethylamine were added under nitrogen. The solution was stirred for 10 min at room
temperature before CuI (7 mg, 0.035 mmol) was added in one portion. After overnight stirring at
room temperature, triethylammonium iodide precipitated from solution, which was separated by
filtration. Toluene was evaporated on a rotary evaporator and the resulting yellow residue was
purified by column chromatography on silica gel, eluting initially with 3% ethyl acetate in
hexane and subsequently increasing polarity of the eluting solvent by using 6% ethyl acetate in
hexane to isolate the desired complexes (3 or 4) as a white solid.
1
1,4ꢀbis[transꢀPt(PEt3)2I(ethynyl)]benzene (3). Yield: 180 mg, 61%; H NMR (CDCl3, 400
MHz): δ 7.14 (s, 4H, ArꢀH), 2.25ꢀ2.17 (m, 24H, ꢀCH2ꢀ), 1.20ꢀ1.12 (m, 36H, ꢀCH3). 31P{1H}
13
NMR (CDCl3, 162 MHz): δ 8.41 (1JPPt = 1164 Hz). C{1H} NMR (CDCl3, 100 MHz): δ 131.5,
130.3, 125.4, 100.4, 29.4, 16.6, 8.4. IR (ATR): 2118 cm−1 for ethynyl group. For C34H64I2P4Pt2:
C, 32.91; H, 5.20. Found: C, 32.85; H, 5.27.
1
4,4ꢀBis[transꢀPt(PEt3)2I(ethynyl)]biphenyl (4). Yield: 125 mg, 64%; H NMR (CDCl3, 400
MHz): δ 7.46ꢀ7.44 (d, J = 8.32 Hz, 4H, ArꢀH), 7.34ꢀ7.31 (d, J = 8.32 Hz, 4H, ArꢀH), 2.27ꢀ2.20
31
(m, 24H, ꢀCH2ꢀ), 1.22ꢀ1.14 (m, 36H, ꢀCH3). P{1H} NMR (CDCl3, 162 MHz): δ 8.50 (1JPPt
=
1163Hz). 13C{1H} NMR (CDCl3, 100 MHz): δ 137.8, 131.0, 127.4, 126.4, 100.1, 90.6, 16.6, 8.3.
IR (ATR): 2135 cm−1 for an ethynyl group. C40H68I2P4Pt2: C, 36.48; H, 5.20. Found: C, 36.61; H,
5.35.

Page 11 of 17
RSC Advances
View Article Online
DOI: 10.1039/C5RA21484J
General procedure for the self assembly of macrocycles 5, 6, 7 and 8.
To the solution of respective organometallic complex (3 or 4, 0.024 mmol) in chloroform (5ml),
was added methanolic solution (3ml) of AgNO3 (0.048 mmol) and the reaction mixture was
stirred for 4h in the dark at room temperature. The precipitated AgI was filtered off over a bed of
celite. To the filtrate thus obtained, was added (dropwise) a methanolic solution (3ml) of a
pyrazine based linker (1 or 2, 0.024 mmol). The reaction mixture was stirred overnight at room
temperature, and subsequently solvents were removed under reduced pressure to obtain a
yellowish solid that was washed twice with diethyl ether and finally dried in vacuum. This
product thus obtained was recrystallized from a mixture of chloroform and methanol to obtain
the desired macrocycles as yellowish microcrystalline solid.
1
Macrocycle 5. Yield: 26 mg, 86%; H NMR (400 MHz, MeOD): δ 8.88 (s, 12H, ArꢀH), 8.83ꢀ
8.79 (m, 24H, ArꢀH), 7.83ꢀ7.82 (d, J = 6.16 Hz, 24H, ArꢀH), 7.08 (s, 24H, ArꢀH), 1.81ꢀ1.75 (m,
31
144H, ꢀCH2ꢀ), 1.16ꢀ1.08 (m, 216H, ꢀCH3). P{1H} NMR (162 MHz, MeOD): δ 15.57 (1JPPt
=
1157 Hz). 13C{1H} NMR (CD3OD, 100 MHz): δ 152.9, 148.1, 147.5, 138.3, 131.8, 131.0, 129.7.
128.1, 126.1, 98.3, 92.9, 86.1, 29.1, 13.8, 6.8. IR (ATR): 2974, 2932, 2883, 2127, 1609, 1510,
1453, 1330, 1149, 1042, 828 cmꢀ1. Anal. Calcd. For C312H444N36O36P24Pt12: C, 49.21; H, 5.88; N,
4.41. Found: C, 49.28; H, 5.93; N, 4.44. MS (ESI) m/z: 2026.59 [5ꢀ4NO3]4+, 1330.40 [5ꢀ
6NO3]6+, 982.30 [5ꢀ8NO3]8+, 866.27 [5ꢀ9NO3]9+, 773.44 [5ꢀ10NO3]10+ and 634.20 [5ꢀ12NO3]12+
.
1
Macrocycle 6. Yield: 25mg, 81%; H NMR (400 MHz, MeOD): δ 8.88 (s, 12H, ArꢀH), 8.83ꢀ
8.81 (m, 24H, ArꢀH), 7.84ꢀ7.82 (d, J = 5.92 Hz, 24H, ArꢀH), 7.49ꢀ7.46 (d, J = 8.36 Hz, 24H, Arꢀ
H), 7.25ꢀ7.23 (d, J = 8.04 Hz, 24H, ArꢀH), 1.82ꢀ1.75 (m, 144H, ꢀCH2ꢀ), 1.18ꢀ1.10 (m, 216H, ꢀ
31
CH3). P{1H} NMR (162 MHz, MeOD): δ 15.61 (1JPPt = 1160 Hz). 13C{1H} NMR (CD3OD,
100 MHz): δ 152.9, 149.2, 147.1, 139.6, 137.9, 132.8, 130.3, 129.7, 128.4, 100.7, 94.3, 91.6,
87.8, 13.8, 6.7. IR (ATR): 2974, 2941, 2883, 2118, 1609, 1502, 1460, 1337, 1149, 1033, 1009,
820 cmꢀ1. Anal. Calcd. For C348H468N36O36P24Pt12: C, 51.78; H, 5.84; N, 4.16. Found: C, 51.95;
H, 5.98; N, 4.32. MS (ESI) m/z: 2140.64 [6ꢀ4NO3]4+, 1406.43 [6ꢀ6NO3]6+, 1196.65 [6ꢀ7NO3]7+,
1039.32 [6ꢀ8NO3]8+, 916.95 [6ꢀ9NO3]9+, 819.06 [6ꢀ10NO3]10+, 738.96 [6ꢀ11NO3]11+ and 672.22
[6ꢀ12NO3]12+
.
1
Macrocycle 7. Yield: 28mg, 90%; H NMR (400 MHz, MeOD): δ 9.06 (s, 4H, ArꢀH), 9.04 (s,
4H, ArꢀH), 8.99ꢀ8.79 (m, 4H, ArꢀH), 8.30ꢀ8.26 (m, 4H, ArꢀH), 7.74ꢀ7.71 (m, 4H, ArꢀH), 7.08 (s,
8H, ArꢀH), 1.81ꢀ1.75 (m, 48H, ꢀCH2ꢀ), 1.23ꢀ1.09 (m, 72H, ꢀCH3). 31P{1H} NMR (162 MHz,
13
MeOD): δ 15.53 (1JPPt = 1156 Hz). C{1H} NMR (CD3OD, 100 MHz): δ 154.6, 153.0, 146.8,
138.3, 131.4, 130.4, 128.4, 125.0, 122.6, 93.6, 89.8, 86.1, 29.1, 13.9, 6.8. IR (ATR): 2965, 2908,
2875, 2120, 1584, 1444, 1411, 1370, 1247, 1033, 836 cmꢀ1. Anal. Calcd. For
C104H148N12O12P8Pt4: C, 49.21; H, 5.88; N, 4.41. Found: C, 49.25; H, 5.91; N, 4.46. MS (ESI)
m/z: 2722.84 [7ꢀNO3] +, 1330.42 [7ꢀ2NO3]2+, 866.28 [7ꢀ3NO3]3+ and 634.21 [7ꢀ4NO3]4+.
1
Macrocycle 8. Yield: 27mg, 87%; H NMR (400 MHz, MeOD): δ 9.07 (s, 4H, ArꢀH), 8.87 (s,
4H, ArꢀH), 8.86ꢀ8.79 (m, 4H, ArꢀH), 8.29ꢀ8.27 (d, J = 8Hz, 4H, ArꢀH), 7.75ꢀ7.71 (m, 4H, ArꢀH),
7.48ꢀ7.46 (d, J = 8.2Hz, 8H, ArꢀH), 7.25ꢀ7.23 (d, J = 8.12Hz, 8H, ArꢀH), 1.83ꢀ1.75 (m, 48H, ꢀ
31
CH2ꢀ), 1.21ꢀ1.10 (m, 72H, ꢀCH3). P{1H} NMR (162 MHz, MeOD): δ 15.56 (1JPPt = 1159 Hz).
13C{1H} NMR (CD3OD, 100 MHz): δ 154.6, 153.0, 147.5, 146.8, 138.3, 137.8, 131.0, 128.7,
127.7, 126.1, 122.6, 89.8, 86.1, 83.6, 82.0, 13.9, 6.8. IR (ATR): 2974, 2932, 2883, 2115, 1617,
1477, 1411, 1337, 1149, 1042, 828 cmꢀ1. Anal. Calcd. For C116H156N12O12P8Pt4: C, 51.78; H,

RSC Advances
Page 12 of 17
View Article Online
DOI: 10.1039/C5RA21484J
5.84; N, 4.16. Found: C, 51.88; H, 5.95; N, 4.29. MS (ESI) m/z: 1406.43 [8ꢀ2NO3]2+, 916.95 [8ꢀ
3NO3]3+ and 672.22 [8ꢀ4NO3]4+.
SingleꢀCrystal Structure Determination for compound 1.
A suitable single crystal of compound 1 was carefully selected under a polarizing microscope
and mounted at the tip of the thin glass fiber using cyanoacrylate (super glue) adhesive. Single
crystal Xꢀray data was collected on a Bruker Smart Apex II diffractometer equipped with an
Oxford Cryostream lowꢀtemperature device and a fineꢀfocus sealedꢀtube Xꢀray source (MoꢀKα
radiation, λ = 0.71073 Å, graphite monochromated) operating at 50 kV and 30 mA. Raw data
collection and refinement were done using SMART. Data reduction was performed using
SAINT14 and corrected for Lorentz and polarization effects. An empirical absorption correction
based on symmetry equivalent reflections was applied using SADABS.15 The structure was
solved by direct methods using SHELXSꢀ97,16 which enabled us to locate the nonꢀhydrogen (C,
N) positions from the difference Fourier maps. For the final refinement, hydrogen atom of
compound 1 was placed geometrically and held in the riding mode. The last cycles of refinement
included atomic positions, anisotropic thermal parameters for all the nonꢀhydrogen atoms,
isotropic thermal parameters for all the hydrogen atoms. Fullꢀmatrix leastꢀsquares structure
refinement against F2 was carried out using the SHELXTLꢀPLUS17 package of programs.
Details of the structure determination and final refinements of 1 listed below.
Crystal Data of 1 : C18H10N4, M = 282.30, Monoclinic, space group C2/c, a = 22.8914(8)Å, b =
5.7531(2)Å, c = 23.2380(7)Å , β = 113.464(4)o , V = 2807.30(16) Å3 , T = 296 K, Z= 8, Dcalc
=
1.336 Mgmꢀ3,
ꢀ
= 0.083 mmꢀ1, 29111 reflections measured , 4277 unique [Rint = 0.0386], R1 [I >
2σ(I)] = 0.0431, wR2 (F , all data) = 0.1214, GOF(F2) = 1.053, CCDC 1032260.
ASSOCIATED CONTENT
Supporting Information
13
1
31
1H and C{1H} NMR spectra of organic molecules 1 and 2, H and P{1H} NMR spectra of
organometallic complexes 3 and 4, H, 31P{1H} and H DOSY NMR spectra of the
metallamacrocycles 5ꢀ8, ESIꢀTOFꢀMS of 5ꢀ8, Xꢀray crystallography analysis of ligand 1 and
detailed simulation protocol. CCDC contains the supplementary crystallographic data for this
paper with a deposition number of CCDC 1032260 (1). Copies of this information can be
obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB21EZ, UK.
[Fax: +44ꢀ1223/336ꢀ033; Eꢀmail: deposit@ccdc.cam.ac.uk].
1
1
AUTHOR INFORMATION
Corresponding Authors:
*Eꢀmail (ND): neeladri@iitp.ac.in or neeladri2002@yahoo.co.in. Tel.: +916122552023. Fax:
+916122277383.
Author Contributions
N.D. conceived the research and supervised the experimental work. S.B. synthesized all
compounds reported in this manuscript. S.C. optimized the energyꢀminimized geometry of the
metallacycles 5ꢀ8. J.N.B. and S.R.M collected XRD data and refined structure of 1.
Notes

Page 13 of 17
RSC Advances
View Article Online
DOI: 10.1039/C5RA21484J
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
N.D. thanks the Indian Institute of Technology (IIT) Patna for financial support. S.B. thanks IIT
Patna for an Institute Research Fellowship. The authors also acknowledge Central NMR Facility,
CSIRꢀNCL for DOSY NMR spectra. The authors also acknowledge Dr. Sivaramaiah Nallapeta
(Bruker Daltonics India) for ESIꢀTOF mass spectrometric data. The authors also acknowledge
SAIFꢀPanjab University for analytical facilities.
Reference:
1. (a) T. R. Cook and P. J. Stang, Chem. Rev. 2015, DOI: 10.1021/cr5005666. (b) T. R. Cook,
Y.ꢀR. Zheng and P. J. Stang, Chem. Rev. 2013, 113, 734. (c) A. Schoedel and M. J.
Zaworotko, Chem. Sci. 2014, 5, 1269. (d) S. Tanaka, H. Tsurugi and K.Mashima, Coord.
Chem. Rev. 2014, 265, 38. (e) I. A. Riddell, M. M. J. Smulders, J. K. Clegg, Y. R. Hristova,
B. Breiner, J. D. Thoburn and J. R. Nitschke, Nat. Chem. 2012, 4, 751. (f) S. Turega, M.
Whitehead, B. R. Hall, M. F. Haddow, C. A. Hunter and M. D. Ward, Chem.Commun. 2012,
48, 2752. (g) R. A. Bilbeisi, J. C. Olsen, L. J. Charbonniere and A. Trabolsi, Inorg. Chim.
Acta 2014, 417, 79. (h) G. Kumar and R. Gupta, Chem. Soc. Rev. 2013, 42, 9403. (i) C. E.
Housecroft, Dalton Trans. 2014, 43, 6594. (j) A. Schmidt, A. Casini and F. E. Kuhn, Coord.
Chem. Rev. 2014, 275, 19. (k) C. A. Palma, M. Cecchini and P. Samori, Chem. Soc. Rev.
2012, 41, 3713. (l) R. Chakrabarty, P. S. Mukherjee and P. J. Stang, Chem. Rev. 2011, 111,
6810. (m) X. Yan, T. R. Cook, P. Wang, F. Huang and P. J. Stang, Nat. chem. 2015, 7, 342.
(n) K. Harris, D. Fujita and M. Fujita, Chem. Commun. 2013, 49, 6703. (o) L. Xu, YꢀX.
Wang, LꢀJ. Chen and HꢀB. Yang, Chem. Soc. Rev. 2015, 44, 2148. (p) S. Li, J. Huang, T. R.
Cook, J. B. Pollock, H. Kim, KꢀW. Chi and P. J. Stang, J. Am. Chem. Soc. 2013, 135, 2084.
2. (a) L. Chen, Q. Chen, M. Wu, F. Jiang and M. Hong, Acc. Chem. Res. 2015, 48, 201. (b) M.
Han, D. M. Engelhard and G. H. Clever, Chem. Soc. Rev. 2014, 43, 1848. (c) S. Chakraborty,
S. Mondal, Q. Li and N. Das, Tetrahedron Lett. 2013, 54, 1681. (d) M. D. Ward and P. R.
Raithby, Chem. Soc. Rev. 2013, 42, 1619. (e) S. Liu, Y.ꢀF. Han and G.ꢀX. Jin, Chem. Soc.
Rev. 2007, 36, 1543. (f) A. Galstyan, M. P. J. Sanz, Katrin. Weise and B. Lippert, Dalton
Trans. 2013, 42, 16151. (g) F. M. Alberti, W. Zielinski, M. Morell Cerda, P. J. Sanz Miguel,
O. Troeppner, I. IvanovicꢀBurmazovic and B. Lippert, Chem. Eur. J. 2013, 19, 9800. (h) Y.
Li, Z. Jiang, J. Yuan, D. Liu, T. Wu, C. N. Moorefield, G. R. Newkome and P. Wang, Chem.
Commun. 2015, 51, 5766. (i) R. Sarkar, K. Guo, C. N. Moorefield, M. J. Saunders, C.
Wesdemiotis and G. R. Newkome, Angew. Chem, Int. Ed. 2014, 53, 12182. (j) J. M. Ludlow,
M. Tominaga, Y. Chujo, A. Schultz, X. Lu, T. Xie, K. Guo, C. N. Moorefield, C.
Wesdemiotis and G. R. Newkome, Dalton Trans. 2014, 43, 9604. (k) M. L. Saha, S. Neogi
and M. Schmittel, Dalton Trans. 2014, 43, 3815. (l) Y. Han, JꢀR. Li, Y. Xie and G. Guo,
Chem. Soc. Rev. 2014, 43, 5952. (m) Z. J. Yao, W. B. Yu, Y. J. Lin, S. L. Huang, Z. H. Li
and G. X. Jin, J. Am. Chem. Soc. 2014, 136, 2982. (n) S. L. Huang, Y. J. Lin, Z. H. Li and G.
X. Jin, Angew. Chem. Int. Ed. 2014, 53, 11218. (o) Y. Han, W. Jia, W. Yu and G. Jin, Chem.
Soc. Rev. 2009, 38, 3419. (p) J. J. Perry, J. A. Perman and M. J. Zaworotko, Chem. Soc. Rev.
2009, 38, 1400. (q) B. Sun, M. Wang, Z. Lou, M. Huang, C. Xu, X. Li, LꢀJ. Chen, Y. Yu, G.
L. Davis, B. Xu and HꢀB. Yang, J. Am. Chem. Soc. 2015, 137, 1556. (r) G.ꢀL. Wang, Y.ꢀJ.

RSC Advances
Page 14 of 17
View Article Online
DOI: 10.1039/C5RA21484J
Lin, H. Berke and G.ꢀX. Jin, Inorg. Chem. 2010, 49, 2193. (s) S. Sato, T. Murase and M.
Fujita, In Selfꢀassembly of coordination cages and spheres; P. A. Gale and J. W. E. Steed,
Supramolecular Chemistry: From Molecules to Nanomaterials; 2012, 5, 2071.
3. (a) Y.ꢀF. Han and GꢀX. Jin, Acc. Chem. Res. 2014, 47, 3571. (b) D. Curiel, M. MasꢀMontoya,
G. Sanchez, R. A. Orenes, P. Molina and A. Tarraga, Org. Biomol. Chem. 2010, 8, 4811. (c)
X. Lu, X. Li, Y. Cao, A. Schultz, J.ꢀL. Wang, C. N. Moorefield, C. Wesdemiotis, S. Z. D.
Cheng and G. R. Newkome, Angew. Chem., Int. Ed. 2013, 52, 7728. (d) M. Schmittel and B.
He, Chem. Commun. 2008, 4723. (e) M. Schmittel, B. He and P. Mal, Org. Lett. 2008, 10,
2513. (f) T. Nakamura, H. Ube, M. Shiro and M. Shionoya, Angew. Chem., Int. Ed. 2013, 52,
720. (g) J.ꢀL. Wang, X. Li, X. Lu, I.ꢀF. Hsieh, Y. Cao, C. N. Moorefield, C. Wesdemiotis, S.
Z. D. Cheng and G. R. Newkome, J. Am. Chem. Soc. 2011, 133, 11450. (h) TꢀZ. Xie, SꢀY.
Liao, K. Guo, X. Lu, X. Dong, M. Huang, C. N. Moorefield, S. Z. D. Cheng, X. Liu, C.
Wesdemiotis and G. R. Newkome, J. Am. Chem. Soc. 2014, 136, 8165. (i) L. Xu, LꢀJ. Chen
and HꢀB. Yang, Chem. Commun. 2014, 50, 5156.
4. (a) D. Samanta and P. S. Mukherjee, Dalton Trans. 2013, 42, 16784. (b) S. Shanmugaraju, A.
K. Bar, H. Jadhav, D. Moon and P. S. Mukherjee, Dalton Trans. 2013, 42, 2998. (c) S.
Chakraborty, S. Mondal, S. Bhowmick, J. Ma, H. Tan, S. Neogi and N. Das, Dalton Trans.
2014, 43, 13270. (d) S. Chakraborty, S. Bhowmick, J. Ma, H. Tan and N. Das, Inorg. Chem.
Front., 2015, 2, 290. (e) J. E. M. Lewis, A. B. S. Elliott, C. J. McAdam, K. C. Gordon and J.
D. Crowley, Chem. Sci. 2014, 5, 1833. (f) S. Li, J. Huang, F. Zhou, T. R. Cook, X. Yan, Y.
Ye, B. Zhu, B. Zheng and P. J. Stang, J. Am. Chem. Soc. 2014, 136, 5908. (g) D. Fujita, H.
Yokoyama, Y. Ueda, S. Sato and M. Fujita, Angew. Chem. Int. Ed. 2015, 54, 15.
5. (a) F. Alberto, LꢀT. Margarita, J. F. Jesus, VꢀG. Digna and V. J. Jose M, Chem. Educ. 2012,
89, 156. (b) X. H. Chang, Y. Wang, Y. C. Jiang, Y. L. Guo, D. D. Song, X. M. Song and F. J.
Verpoort, Organomet. Chem. 2012, 713, 134. (c) F. A. Pereira, T. Fallows, M. Frank, A. Q.
Chen and G. H. Clever, Z. Anorg. Allg. Chem. 2013, 639, 1598. (d) Q.ꢀF. Sun, S. Sato and
M. Fujita, Angew. Chem., Int. Ed. 2014, 53, 13510. (e) I. Angurell, M. Ferrer, A. Gutiérrez,
M. Martínez, M. Rocamora, L. Rodríguez, O. Rossell, Y. Lorenz and M. Engeser, Chem.
Eur. J. 2014, 20, 14473. (f) D. Fujita, H. Yokoyama, Y. Ueda, S. Sato and M. Fujita, Angew.
Chem., Int. Ed. 2015, 54, 155. (g) MꢀE. G. Topić, F. Schnakenburg, G. Rissanen and K.
Lützen, A. Eur. J. Inorg. Chem. 2014, 2495. (h) M. D. Wise, J. J. Holstein, P. Pattison, C.
Besnard, E. Solari, R. Scopelliti, G. Bricogne and K. Severin, Chem. Sci. 2015, 6, 1004. (i) J.
K. Kilpin, M. L. Gower, S. G.Telfer, G. B. Jameson and J. D. Crowley, Inorg.Chem. 2011,
50, 1123. (j) D. C. Hamm, L. A. Braun, A. N. Burazin, A. M. Gauthier, K. O. Ness, C. E.
Biebel, J. S. Sauer, R. Tanke, B. C. Noll, E. Bosch and N. P. Bowling, Dalton Trans. 2013,
42, 948. (k) S. Ghosh, S. R. Batten, D. R. Turner and P. S. Mukherjee, Organometallics
2007, 26, 3252. (l) L. Zhao, B. H. Northrop, YꢀR. Zheng, H.ꢀB. Yang, H. J. Lee, Y. M. Lee,
J. Y. Park, KꢀW. Chi and P. J. Stang, J. Org. Chem. 2008, 73, 6580. (m) L. Rodrígueza, M.
Ferrera, O. Rossella and S. Cocob, Journal of Organometallic Chemistry 2009, 694, 3951(n)
L. R. Holloway, M. C. Young, G. J. O. Beran and R. J. Hooley, Chem. Sci. 2015, 6, 4801. (o)
K. Harris, Q.ꢀF. Sun, S. Sato and M. Fujita, J. Am. Chem. Soc. 2013, 135, 12497. (p) T.
Sawada, H. Hisada and M. Fujita, J. Am. Chem. Soc. 2014, 136, 4449. (q) A. Baba, T.
Kojima, S. Hiraoka, J. Am. Chem. Soc. 2015, 137, 7664.

Page 15 of 17
RSC Advances
View Article Online
DOI: 10.1039/C5RA21484J
6. (a) K. Li, T. Zou, Y. Chen, X. Guan and CꢀM. Che, Chem. Eur. Jour. 2015, 21, 7441. (b) Y.
Chen, CꢀM. Che and W. Lu, Chem. Commun. 2015, 51, 5371. (c) F. Zhou, S. Li, T. R. Cook,
Z. He and P. J. Stang, Organometallics 2014, 33, 7019. (d) I. V. Grishagin, J. B. Pollock, S.
Kushal, T. R. Cook, P. J. Stang and B. Z. Olenyuk, Proc. Natl. Acad. Sci. 2014, 111, 18448.
(e) P. S. Mukherjee, S. Pramanik and S. Shanmugaraju, In Pt/Pd ethynyl bond containing
fluorescent molecular architectures as sensors for nitroaromatics in Molecular Selfꢀ
Assembly: Advances and Applications; A. D. Q. Li, Ed.; Pan Stanford Publishing: Singapore,
2013, 259. (f) L. Xu, YꢀX. Wang and HꢀB. Yang, Dalton Trans. 2015, 44, 867. (g) S.
Shanmugaraju, S. A. Joshi and P. S. Mukherjee, Inorg. Chem. 2011, 50, 11736. (h) N.
Dsouza, U. Pischel and W. M. Nau, Chem. Rev. 2011, 111, 7941. (i) L. E. Kreno, K. Leong,
O. K. Farha, M. Allendorf, R. P. Van Duyne and J. T. Hupp, Chem.Rev. 2012, 112, 1105. (j)
Y. Cui, Y. Yue, G. Qian and B. Chen, Chem.Rev. 2012, 112, 1126. (k) H. R. Moon, D.ꢀW.
Lim and M. P. Suh, Chem. Soc. Rev. 2013, 42, 1807. (l) Z. Hu, B. J. Deibert and J. Li, Chem.
Soc. Rev. 2014, 43, 5815. (m) B. Liu, J. Mater. Chem. 2012, 22, 10094.
7. (a) M. Yoshizawa and J. K. Klosterman, Chem. Soc. Rev. 2014, 43, 1885. (b) C. G. Oliveri,
P. A. Ulmann, M. J. Wiester and C. A. Mirkin, Acc. Chem. Res. 2008, 41, 1618. (c) G. R.
Newkome and C. Shreiner, Chem. Rev. 2010, 110, 6338. (d) P. J. Stang and B. Olenyuk, Acc.
Chem. Res. 1997, 30, 502. (e) S. Leininger, B. Olenyuk and P. J. Stang, Chem. Rev. 2000,
100, 853. (f) Y. Takezawa and M. Shionoya, Acc. Chem. Res. 2012, 45, 2066. (g) M. Fujita,
M. Tominaga, A. Hori and B. Therrien, Acc. Chem. Res. 2005, 38, 369. (h) Y. Inokuma, M.
Kawano and M. Fujita, Nat. Chem. 2011, 3, 349.
8. (a) K. Manna, T. Zhang, F. X. Greene and W. Lin, J. Am. Chem. Soc. 2015, 137, 2665. (b) K.
Lu, C. He and W. Lin, J. Am. Chem. Soc. 2014, 136, 16712. (c) LꢀJ. Chen, GꢀZ. Zhao, Bo.
Jiang, Bin. Sun, M. Wang, Lin. Xu, J. He, Z. Abliz, H. Tan, X. Li and HꢀB. Yang, J. Am.
Chem. Soc., 2014, 13, 5993. (d) N. Kishi, M. Akita, M. Kamiya, S. Hayashi, H.ꢀF. Hsu and
M. Yoshizawa, J. Am. Chem. Soc. 2013, 135, 12976. (e) H.ꢀB. Yang, K. Ghosh, Y. Zhao, B.
H. Northrop, M. M. Lyndon, D. C. Muddiman, H. S. White and P. J. Stang, J. Am.Chem. Soc.
2008, 130, 839. (f) D. Liu, K. Lu, C. Poon and W. Lin, Inorg. Chem. 2014, 53, 1916. (g) H.
J. Yoon, J. Heo and C. A. Mirkin, J. Am. Chem. Soc. 2007, 129, 14182. (h) T. Chen, G.ꢀB.
Pan, H. Wettach, M. Fritzsche, S. Höger, L.ꢀJ. Wan, H.ꢀB. Yang, B. H. Northrop and P. J.
Stang, J. Am. Chem. Soc. 2010, 132, 1328.
9. S. Bhowmick, S. Chakraborty, A. Das, P. R. Rajamohanan and N. Das, Inorg. Chem. 2015,
54, 2543.
10. (a) J. Zhang, R. Marega, LꢀJ. Chen, NꢀW. Wu, XꢀD. Xu, D. C. Muddiman, D. Bonifazi and
HꢀB. Yang, Chem.ꢀAsian J. 2014, 9, 2928. (b) L. Zhao, B. H. Northrop and P. J. Stang, J.
Am. Chem. Soc. 2008, 130, 11886. (c) E. Coronado, J. R. GalanꢀMascaros, P. Gavina, C.
MartiꢀGastaldo, F. M. Romero and S. Tatay, Inorg. Chem. 2008, 47, 5197.
11. (a) W. Wang, B. Sun, X. Q. Wang, Y. Y. Ren, L. J. Chen, J. Ma, Y. Zhang, X. Li, Y. Yu, H.
Tan and HꢀB. Yang, Chem. Eur. J. 2015, 21, 6286. (b) NꢀW. Wu, LꢀJ. Chen, C. Wang, YꢀY.
Ren, X. Li, L. Xu and HꢀB. Yang, Chem. Commun. 2014, 50, 4231. (c) W. Wang, Y. Zhang,

RSC Advances
Page 16 of 17
View Article Online
DOI: 10.1039/C5RA21484J
B. Sun, LꢀJ. Chen, XꢀD. Xu, M. Wang, X. Li, Y. Yu, W. Jiang and HꢀB. Yang, Chem. Sci.
2014, 5, 4554. (d) HꢀB. Yang, N. Das, F. Huang, A. M. Hawkridge, D. C. Muddiman and P.
J. Stang, J. Am. Chem. Soc. 2006, 128, 10014.
12. S. Bhowmick, S. Chakraborty, A. Das, S. Nallapeta, and N. Das Inorg. Chem. 2015, 54,
8994.
13. SAINT, Version 6.02; Bruker AXS, Inc: Madison, WI, 2001.
14. SADABS; Bruker AXS, Inc: Madison, WI, 2001.
15. G. M. Sheldrick, SHELXLꢀ97; University of Gottingen: Gottingen, Germany, 1997.
16. G. M. Sheldrick, SHELXTLꢀPLUS Program for Crystal Structure Solution and Refinement;
University of Gottingen: Gottingen, Germany, 1997.

Page 17 of 17
RSC Advances
View Article Online
DOI: 10.1039/C5RA21484J
Table of Contents Synopsis and Graphic
PyrazineꢀBased Donor Tectons: Synthesis, SelfꢀAssembly and Characterization
Sourav Bhowmick,1 Sourav Chakraborty,1 Subba R. Marri,2 J. N. Behera2 and Neeladri Das1*
1Department of Chemistry, Indian Institute of Technology Patna, Bihar, India
2School of Chemical Sciences, National Institute of Science Education and Research (NISER),
Bhubaneswar 751005, India
Two supramolecular donor tectons, wherein a central pyrazine unit is covalently linked to two
pyridine moieties, have been synthesized. In conjugation with PtII acceptor units, these ligands
2
have been used to selfꢀassemble four ionic nanoscalar metallamacrocycles, each having a convex
hexagonal cavity.