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Self-Assembly of Molecular Prisms via Pt 3 Organometallic Acceptors and a Pt 2 Organometallic Clip Sushobhan Ghosh, Bappaditya Gole, Arun Kumar Bar, and Partha Sarathi Mukherjee* Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore-560 012, India.

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advanced instrumental analysis lab ji eun park 09 08 13

Self-Assembly of Molecular Prisms via Pt3 Organometallic Acceptorsand a Pt2 Organometallic ClipSushobhan Ghosh, Bappaditya Gole, Arun Kumar Bar, and Partha Sarathi Mukherjee*Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore-560 012, India

Ref) Organometallics, Vol. 28, No. 15, 2009

Advanced Instrumental Analysis lab

Ji Eun Park

09.08.13

slide2

Introduction

solution fluorescence  quenched efficiently by adding nitroaromatics

 chemical signatures

4,4’,4’’-tris[ethynyl-trans-Pt-

(PEt3)2(NO3)]triphenylamine

+1,3-bis(3pyridylethynyl)benzene

 trigonal prism

4,4’,4’’-tris(4-pyridylethynyl)

triphenylamine + organometallic Pt2-clip  3c

Ref) (a) Ghosh, S.; Mukherjee, P. S. Organometallics 2008, 27, 316.

Schultheiss, N.; Ellsworths, J. M.; Bosch, E.; Barnes, C. L. Eur. J.Inorg. Chem. 2005, 45.

slide3

Introduction

new tripodal Pt3-organometallic acceptor 

4,4’,4’’-tris[ethynyl-trans-Pt(PEt3)2(NO3)]triphenylethane + [1,8-bis(4-pyridylethynyl)anthracene] [2 + 3]  self-assembled prismatic derivative

slide4

Results

Synthesis of the Linkers

Ref) (a) Ghosh, S.; Mukherjee, P. S. Organometallics 2008, 27, 316.

Kryschenko, Y. K.; Seidel, R. S.; Muddiman, D. C.; Nepomuceno,A. I.; Stang, P. J. J. Am. Chem. Soc. 2003, 125, 9647

slide5

Results

Synthesis of the Linkers

31P{1H}NMR 195Pt

ESI mass spectrum

molecular ion [M+H+] m/z =1807.5

[M-4PEt3-NO3-]+ fragment m/z = 1274

slide6

Results

Synthesis of the Linkers

· Cell dimensions of 1c  crystal system, cubic; space group, Pa ; α = 25.4754(5) Å; R=90°

· The optimization of the tripodal linker

density functional theory (DFT) calculations

Gaussian 03 program, B3LYP functional

· 6-31G for lighter elements (C, H, N, and O) & LanL2DZ for heavier elements (Pt and P).

· X-ray structure analysis

 I-C(central)-I angle ;110.97°

· Pt environment angles 86.44° and 93.11°,

Ref) Kryschenko, Y. K.; Seidel, R. S.; Muddiman, D. C.; Nepomuceno,A. I.; Stang, P. J. J. Am. Chem. Soc. 2003, 125, 9647

slide7

Results

Self-Assembly of Molecular Prisms 3a-d

trigonal prism design ; two tritopic donors, six 90°corners, three linear linkers  [2+6+3] self-assembly reaction

The major disadvantage of three-component self-assembly formation of a mixture

slide8

Results

Self-Assembly of Molecular Prisms 3a-d

3b ; yellow precipitate

31P NMR

- solvent;CDCl3

- singlet at 15.6 ppm

- 1JP-Pt (230 Hz) for the Pt satellites.

slide9

Results

Self-Assembly of Molecular Prisms 3a-d

  • 31P{1H} NMA ;singlet , 14ppm
  • 5 ppm upfield
  • shifted from the 31P{1H}NMR ; 1b
slide10

Results

Self-Assembly of Molecular Prisms 3a-d

Upfield shift ; phosphorus signal of 1c

downfield shift ; Hα, Hβ, H9 protons of the donor ligand

slide11

Results

Self-Assembly of Molecular Prisms 3a-d

  • 3a:
  • [M3a- 3NO3]3+
  • m/z=1452.00 (calcd 1451.66)
  • [M3a- 4NO3]4+
  • m/z=1073.49 (calcd 1073.18)
  • [M3a-5NO3]5+
  • m/z=846.55 (calcd 845.67)

Ref) (a) Ghosh, S.; Mukherjee, P. S. Organometallics 2008, 27, 316.

slide12

Results

Self-Assembly of Molecular Prisms 3a-d

  • [M3b-3NO3-]3+
  • isotropic distribution pattern of the peak ,
  • matched well with the theoretically expected pattern
slide13

Results

Self-Assembly of Molecular Prisms 3a-d

slide14

Results

Self-Assembly of Molecular Prisms 3a-d

[M3d-3NO3]3+ m/z=1523.50 (calcd 1523.33)

[M3d -5NO3]5+

m/z =890.1 (calcd 889.3)

slide15

Results

Self-Assembly of Molecular Prisms 3a-d

Obtain single crystals for X-ray diffraction  fail

Supramolecule 3d

energy minimization is presented

slide16

Results

Absorption and Fluorescence Studies.

3b spectrum ; 1.5×10-5 M solution,

283 nm  π-π* transition

365 nm  metal-to-ligand (2b) charge transfe

3c spectrum ; 3×10-6M solution

430 and 383 nm

 originating from the anthracene moiety of 1b

3d spectrum ;

421 and 398 nm corresponding to the anthracene part

309nm ; attributed to platinum-to-ligand (2d) charge transfer

3b-d  excited at 400 nm ;

luminescent behavior & emit beteen400nm and 500 nm

slide17

Results

Absorption and Fluorescence Studies.

3b-d Fluorescence spectra in DMF solutions

corresponding photophysical data Table S1

slide18

Conclusion

·Pt3 organometallic acceptor (1c) & nanoscopic conjugated prisms (3a-d)

 Pt-ethynyl functionality

· tritopic planar donor (2c) and Pt2-organometallic clip (1b)

 establish the versatility of directional bonding to obtain

· Pt-ethynyl incorporation; assemblies fluorescent.

· conjugated ethynyl functionality

 assemblies π-electron rich and possible hosts

· 3a, 3c, and 3d  chemical signature of many commercial explosives

· Conjugated organic polyethynyl compounds

 potential sensors for chemical explosives.

slide19

Introduction of Heterofunctional Groups onto Molecular Hexagons

via Coordination-Driven Self-Assembly

Koushik Ghosh,† Jiming Hu,†,‡ Hai-Bo Yang,§ Brian H. Northrop,† Henry S. White,*,† and Peter J. Stang*,†

<ref.> J. Org. Chem. 2009, 74, 4828–4833

Young Min Lee

Organic Synthesis Lab.

Department of Chemistry

slide20

Abstract

The design and synthesis of two new heterofunctional hexagons containing both redox-active ferrocenyl and host-guest crown ether functionalities has been achieved via coordination-driven

self-assembly. The size and relative distribution of functional groups on the supramolecular metallacycles can be precisely controlled. The host-guest recognition properties of the crown

ether moieties and their ability to complex cationic guests to form tris[2]pseudorotaxane complexes have been investigated. The functional moieties are shown to operate orthogonally, resulting in

discrete supramolecular hexagons that are capable of carrying out a variety of functions both

simultaneously and independently.

slide21

Introduction

  • The design and creation of regularly shaped nanoscale objects, which can serve as the building blocks of supramolecular materials,
  • is an extremely important goal in material science.
  • They have recently introduced a variety of functionalized 120°
  • platinum acceptors and 120° organic donors and have quantitatively
  • assembled them to form molecular hexagons with six functional
  • groups on their periphery.
  • They envisioned that acceptor-donor-based coordination-driven
  • self-assembly is additionally useful because of the ability to modify
  • functional groups at both the donor and acceptor units.
  • Here they employ 120° acceptor units decorated with one functional group to self-assemble with 120° donor units decorated with another
  • functional group to form supramolecular hexagons with six
  • heterofunctional groups.
slide22

Result

Heterofunctional Hexagons 5 and 6

  • Scheme 1. Self-Assembly of Heterofunctional Hexagons
  • With the 120° crown ether and ferrocene functionalized precursors in hand, in both donor and acceptor analogues, the self-assembly of heterofunctional hexagons was
  • investigated.
  • Upon mixing 120° ferrocenyl donor unit 1 with 120° crown ether functionalized unit 2 in CH2Cl2, heterofunctional hexagon
  • 5 was obtained .
  • Stirring 120° ferrocenyl acceptor
  • unit 3 with an equimolar amount of 120° crown ether donor unit 4 in
  • CH2Cl2 results in heterofunctional
  • hexagon 6.
slide23

Result

Tris[2]Pseudorotaxanes 8 and 9

  • Scheme 2. Entry to Hexagonal Cavity-Cored Tris[2]pseudorotaxanes
  • These heterofunctionalized crown ether derivatives in hand, an investigation of the self-assembly
  • of tris[2]pseudorotaxanes was carried out to investigate any effect(s) of ferrocene substituents in the binding of crown ether
  • units.
  • Within 15 min of adding 3 equiv
  • of dibenzylammonium triflate salt 7 to a solution of hexagonal metallacycles 5 and 6, tris[2]pseudorotaxanes 8 and 9, respectively, were obtained.
slide24

Result

1H and 31P NMR spectra of 5

(a)

195Pt satellites

(b)

< Hexagon 5 >

  • Figure 1. 1H(a) and 31P(b) NMR spectra of 5 in CD2Cl2
slide25

Result

1H and 31P NMR spectra of 6

(a)

(b)

195Pt satellites

< Hexagon 6 >

  • Figure 3. 1H(a) and 31P(b) NMR spectra of 6 in CD2Cl2
slide26

Result

1H and 31P NMR spectra of 8

(a)

195Pt satellites

(b)

< Tris[2]Pseudorotaxanes 8 >

  • Figure 2. 1H(a) and 31P(b) NMR spectra of 8 in CD2Cl2
slide27

Result

1H and 31P NMR spectra of 9

(a)

195Pt satellites

(b)

< Tris[2]Pseudorotaxanes 9 >

  • Figure 4. 1H(a) and 31P(b) NMR spectra of 9 in CD2Cl2
slide28

Result

Partial 1H NMR spectra

  • In the corresponding 1H
  • NMR spectra, the-protons
  • showed a relatively
  • dramatic upfield shift
  • (0.41 ppm) as well as a
  • slight upfield shift of the
  • R-protons (0.04 ppm) due
  • to electron density transfer
  • from the pyridyl donor to
  • the metal acceptor.
  • A 0.45 ppm downfield
  • shift of the signal for the
  • benzylic methylene protons adjacent to the NH2+ center was observed, and protons
  • Hα, Hβ, and Hγ of of the
  • crown ether moiety exhibited upfield shifts.
  • Figure 8. Partial 1H NMR spectra of crown ether acceptor 2 (A), ferrocenyl donor 1 (B), mixed
  • hexagon 5 (C), and pseudorotaxane 8 (D).
slide29

Result

ESI-MS spectra of hexagon 5 and 6

  • In the ESI mass spectra of
  • heterofunctionalized hexagon 5, a peak attributable to the loss of four triflate counterions, [M - 4OTf]4+ where M represents the intact assembly, was observed at
  • m/z = 1563.9.
  • The ESI/MS spectra of 6 exhibited characteristics very similar to those of 5. The ESI/MS spectra showed one charged state at
  • m/z = 1553.4 corresponding to
  • the [M - 4OTf]4+ species, and its isotopic resolution is in excellent agreement with the theoretical
  • distribution.
  • Figure 5. Calculated (top) and experimental (bottom) ESI-MS spectra of hexagon 5 (A) and 6 (B).
slide30

Result

ESI-MS spectra of 8 and 9

  • Figure 6. Calculated (top) and experimental
  • (bottom) ESI-MS spectra of 8.
  • Figure 7. Calculated (top) and experimental
  • (bottom) ESI-MS spectra of 9.
  • The self-assembly of hexagonal cavity-cored tris[2]pseudorotaxanes 8 and 9 was also confirmed by ESI-MS spectrometry.
  • Two peaks at m/z = 1429.4 and 1824.8 were observed, corresponding to [M - 5OTf]5+
  • and [M - 4OTf]4+, respectively, for 8, as were peaks attributable to [M - 5OTf]5+ and
  • [M - 4OTf]4+ of 9 at m/z = 1421.1 and 1813.4, respectively.
slide31

Result

Pseudorotaxane Stoichiometry and Binding Constant

  • The host:guest stoichiometry for
  • heterofunctional supramolecular
  • assemblies 8 and 9 was established
  • using the nonlinear leastsquares
  • fit method based 1H NMR titration
  • experiments.
  • Fitting the data to a 1:3 binding
  • mode for the hosts gave host-guest
  • association constants.
  • Figure 9. 1H NMR titration isotherms of 8 (A) and 9 (B),
  • recorded at 500 MHz in CD2Cl2 at 298 K,
  • indicating the change in chemical shift of the
  • proton signal corresponding to the γ-H of the
  • crown ether.
  • Table 1. Thermodynamic Binding Constants of Poly[2]pseudorotaxanes 8 and 9a
slide32

Result

Simulated molecular models of 5 and 8

  • Figure 10. Simulated molecular models of 5 and 8, optimized with the molecular mechanics
  • force field. Color scheme: C = gray, O = red, N = blue, P = purple, Pt = yellow, and
  • R2NH2+ hydrogen atoms =green, Fe = purple all other hydrogen atoms have been
  • removed for clarity.
slide33

Result

Simulated molecular models of 6 and 9

  • Figure 11. Simulated molecular models of 6 and 9, optimized with the molecular mechanics
  • force field. Color scheme: C = gray, O = red, N = blue, P = purple, Pt = yellow,
  • Fe = pink and R2NH2+ hydrogen atoms, green (all other hydrogen atoms have been
  • removed for clarity).
slide34

Conclusion

  • They have provided two complementary approaches to generate
  • two new heterofunctional hexagons via coordination-driven self-
  • assembly from a ferrocenyl 120° di-Pt(II) acceptor/donor and a
  • complementary 120° crown ether decorated donor/acceptor unit
  • while exhibiting precise control of size and the distribution of the
  • ferrocene and crown ether moieties.
  • These heterofunctional hexagons are unique in not only their
  • discrete structures but also the presence of chemically different
  • units, since each unit introduces into the supramolecular structure
  • its own “pieces of information” (in the form of specific properties
  • such as recognition properties, redox levels, etc.) that are preserved
  • faithfully in the structure.
slide35

A Catalytically Active, Permanently Microporous MOF with Metalloporphyrin

Struts

Abraham M. Shultz, Omar K. Farha, Joseph T. Hupp,* and SonBinh T. Nguyen*

Received January 10, 2009

Undergraduate forth

BAE CHANG GEUN

slide36

Figure 1. Synthesis of ZnPO-MOF. The stick representation of the unit

cell is shown on the right-hand side (yellow polyhedra ) Zn, red ) O,

green ) F, blue ) N, gray ) C). Solvent molecules, hydrogens, and

disordered atoms have been omitted for clarity.

slide39

Figure 2. Space-filling models of the crystal structure of ZnPO-MOF

(solvent omitted) showing channels down the a and b crystallographic axes

(yellow ) Zn, red ) O, green ) F, blue ) N, gray ) C, black ) H): (a)

15 Å × 9 Å channels along the a axis; (b) 11 Å × 9 Å channels along the

b axis. The channels along the c axis (not shown) are 8 Å × 9 Å.

slide41

Figure 3. Plot of product concentrations vs time, showing the initial production

of the various isomers of acetoxymethylpyridine (AMP) from N-acetylimidazole

and pyridylcarbinols. The inset shows data at longer times.

slide42

Conclusion

To summarize, they have demonstrated that by appropriate design of organic building blocks (dipyridyl pillars, robust tetratopic carboxylates), metalloporphyrins can be successfully incorporated into a MOF possessing the features needed for effective catalysis, i.e., large pores, permanent microporosity, and fully reactant-accessible active sites. Proof-of-concept catalysis of an acyl-transfer reaction revealed ∼2400- fold rate enhancement, dominated by contributions from LA activation and reactant preconcentration. They hope to report shortly on variants of ZnPO-MOF featuringother metals as active sites and functioning catalytically by other mechanisms.

slide43

Coordination-Driven Self-Assembly of Metallodendrimers Possessing Well-Defined and Controllable Cavities as Cores

Peter J. Stang* et al.

Department of Chemistry, University of Utah, 315 South 1400 East,

Room 2020, Salt Lake City, Utah 84112

J. AM. CHEM. SOC. 9 VOL. 129, NO. 7, 2007

Kim You-Jung

Undergraduate Junior

introduction
Introduction
  • Supramolecular dendrimers are a recent and important subset of such self-assembled structures.
  • As a consequence, attention has recently turned to the self-assembly of dendrimers to provide well-defined nanoscale architectures via a variety of noncovalent interactions such as electrostatic interactions, hydrogen bonding and metal-ligand coordination.
  • In particular, cavity-cored dendrimers have recently received considerable attention because of their elaborate structures and potential applications in delivery and recognition.
introduction1
Introduction
  • Previously, Percec et al. reported a library of amphiphilic dendritic dipeptides that self-assemble into helical pores both in solution and in bulk.
  • In addition, the possibility to fine-tune the size and shape of the cavities in metallodendrimers would help provide an enhanced understanding of the geometrical requirements necessary for molecular self-assembly.
  • Furthermore, this strategy would likely give rise to the design and synthesis of novel supramolecular species with desired functionality arising from their unique interior cavities and dendritic exteriors.
introduction2
Introduction
  • Recently theyreported the self-assembly of the first metallodendrimers exhibiting a nonplanar hexagonal cavity with an internal core radius of approximately 1.6nm, by the combination of 120° dendritic donor subunits (substituted with Fréchet-type dendrons) and 120° di-Pt(Ⅱ) acceptor angular linkers in a 1:1 stoichiometric ratio.
  • Here they report the results obtained

when they extended the investigations

to the self-assembly of rhomboidal

and “snowflake-shaped” metalloden-

drimers possessing cavities of various

size and shape at the core through

the use of coordination-driven

self-assembly (Figure 1).

result and discussion
Result and Discussion

Synthesis of 120° Angular Dendritic Donor Subunits

The synthesis of [G0]-[G3] 120° donor building blocks

5a-d commenced with acylation of the commercially

available compound 3,5-dibromo-phenol (1) to give 2

(Scheme 1). The 3,5-bis-pyridylethynyl-phenyl ester 3

was prepared by palladium-mediated coupling reaction

from Ester 2 with 4-ethynylpyridine in reasonable yield

(66%). Upon ester hydrolysis and etherification, the [G0]-

[G3] 120° precursors 5a-d (Figure 2), substituted with

Fréchet-type dendrons, were obtained in good yields.

result and discussion1
Result and Discussion

Synthesis of [G0]-[G3]-Rhomboidal

Metallodendrimers 7a-d.

The combination of 60° units with 120° linking

components will yield a molecular rhomboid.

Stirring the [G0]-[G3] 120° angular donors

5a-d with an equimolar amount of the known

60° angular acceptor, 2,9-(trans Pt(PEt3)2NO3)2-

phenanthrene (6), in CD2Cl2 for 14h resulted in

[2+2] rhomboidal metallodendrimers 7a-d,

respectively, in excellent yields (Scheme 2).

result and discussion2

The 31P{1H} NMR spectra of the [G0]-[G3]

assemblies 7a-d displayed a sharp singlet (ca. 14.6

ppm) shifted up field from the signal of the starting

platinum acceptor 6 by approximately 6.4 ppm. This

change, as well as the decrease in coupling of the

flanking 195Pt satellites (ca. ¢J ) –177Hz), is consistent

with back-donation from the platinum atoms.

In the 1H NMR spectrum of each assembly, the R-

hydrogen nuclei of the pyridine rings exhibited 0.75-

0.78 ppm downfield shifts, and the â-hydrogen

nuclei showed about 0.2 ppm downfield shifts, due

to the loss of electron density that occurs upon

coordination of the pyridine N atom with the Pt(II)

metal center. It is noteworthy that two doublets

were observed for these R-hydrogen nuclei, as this

might be attributed to hindered rotation about the

Pt-N(pyridyl) bond, which has been previously

reported.

Result and Discussion
result and discussion3
Result and Discussion

In the ESI mass spectra of the [G0]-[G2] assemblies 7a-c, peaks attributable to the

loss of nitrate counter ions, [M - 2NO3]2+ (m/z ) 1486.9 for 7a, m/z ) 1699.0 for 7b,

and m/z ) 2123.8 for 7c) and [M - 3NO3]3+ (m/z ) 970.5 for 7a, m/z ) 1112.0 for 7b,

and m/z ) 1394.8 for 7c), where M represents the intact assemblies, were observed

(Figure 3)

result and discussion4

The ESI-FTICR mass spectrum of the [G3]

assembly 7d showed two charged states at

m/z ) 1961.4 and 1455.5, corresponding to

the [M-3NO3]3+ and [M – 4NO3]4+ species,

respectively, and their isotopic resolution is

in excellent agreement with the theoretical

distribution (Figure 4). The analysis of the

signals observed in the full mass spectra

confirmed that there was no other assembled

species formed.

Result and Discussion
result and discussion5
Result and Discussion

X-ray crystallographic analysis unambiguously established

the structures of 7a and 7b to be both discrete [G0]- and

[G1]-rhomboidal metallodendritic assembles (Figures 5

and 6). Crystals suitable for single-crystal X-ray analysis

were grown by vapor diffusion of n-pentane into a

CH2Cl2/CH3COCH3 (v/v 1/1) solution of 7a and 7b

respectively at ambient temperatures for 3 days. Both 7a

and 7b crystallize in the triclinic space group P1 but are

not isomorphous to each other, as revealed by their

different unit cell geometries and dimensions.

result and discussion6
Result and Discussion

At the molecular level, both structures feature

a well-defined rhombus with an approximately

2.3 X 1.3 nm cavity that embodies the porosity

of the crystal.

In both structures, this cavity is partially filled

with disordered nitrate anions and solvent

molecules. The rhomboidal structure of 7a has

external dimensions of ca. 3.3 nm long and 2.8

nm wide, while 7b spreads out over an area of

ca. 4.2 X 2.8 nm2. Except for a slight difference

in their conformation, the two molecules 7a

and 7b can almost be superimposed with each

other in their rhomboidal parts (Figure 7).

slide54

Conclusion

  • They have demonstrated that highly convergent synthetic protocols based on the simultaneous assembly of appropriate predetermined building blocks allow the rapid construction of novel cavity-cored metallodendrimers.
  • In particular, this approach makes it possible to prepare a variety of metallodendrimers with well-defined and controlled cavities as cores through the proper choice of subunits with predefined angles and symmetry, which enriches the library of different-shaped cavity-cored metallodendrimers.
  • Furthermore, the shape of the cavities of the supramolecular dendrimers can be rationally designed to be either a rhomboid or a hexagon.
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