1. Metal organic Copolymers containing iron(II) clathrochelate units

Scheme 1. Synthesis of various metal organic ligands and Copolymers containing iron(II) clathrochelate units

The rational design and synthesis of robust metal–organic frameworks (MOFs) based on novel organic building blocks are fundamental aspects of reticular chemistry. In this regard we have we successfully targeted a highly porous and robust cage-type MOF (NU-200) with an nbo-derived fof topology through the deliberate assembly of a cyclohexane-functionalized iron(II) clathrochelate-based meta-benzenedicarboxylate linker with Cu2(CO2)4 secondary building unit (SBU). NU-200 exhibited an outstanding adsorption capacity of xenon (110 cm3 g-1 or 107 cm3 cm-3) and high ideal adsorbed solution theory (IAST) predicted selectivity of 9.3 for a 20/80 v/v mixture of xenon (Xe) / krypton (Kr) at 298 K and 1.0 bar. Additionally, we validated the unique pocket confinement effect by experimentally and computationally employing the similarly sized probe, sulfur dioxide (SO2), which provided significant insights into the molecular underpinnings of the very high uptake of SO2 (11.7 mmol g-1), especially at a low pressure of 0.1 bar (8.5 mmol g-1) [1-2]. We have also reported regulating the catenation of Zn-MOFs based on the primitive cubic (pcu) net, isoreticular to MOF-5, via fine-tuning the clathrochelate-based ditopic building blocks. The use of clathrochelate-based carboxylate ligands with bulky cores of n-butyl groups led to the synthesis of a Zn-MOF with the pcu net while clathrochelate linkers with relatively less bulky cores give a 2-fold interpenetrated Zn-MOF structure under similar conditions [3].

Polyclathrochelate derivatives were obtained using the mild one-step polycondensation reaction of an iron(II) center chelated to three polar furil dioxime side groups and doubly capped with various aryl diborate central spacers. Nitrogen adsorption measurements of the polychlathrochelates (PCL1-4) reveal excellent BET surface area up to 396 m2g -1 [4]. The highly soluble copolymers composed of iron (II) clathrochelate with lateral butyl chains and intercalated by various contorted units containing thioether groups TCP1-3 and selective oxidation of their thioether units into their corresponding sulfone derivatives OTCP1-2 were successfully synthesized. Lithium ions adsorption tests of the target copolymers reveal a maximum adsorption capacity of OCTP2 of 2.31 mg g-1. Furthermore, OTCP2 discloses excellent adsorption capacity for the cationic dye methylene blue (MEB) from the aqueous solutions exhibiting a maximum adsorption capacity (qm) of 480.77 mg g-1 by following Langmuir isotherm model. Kinetic study of MEB adsorption by OTCP2 suggests a pseudo second-order model disclosing an equilibrium adsorption capacity, qe,cal, of 45.40 mg g-1[5].

1.1 Post modification of Metal organic Copolymers containing iron(II) clathrochelate units

Scheme 2. Synthesis of Post modified metal organic Copolymers containing iron(II) clathrochelate units

The first example of making secondary CLP1-3 and tertiary arylamine copolymers PCLP1-3 bearing clathrochelates units via the facile Buchwald-Hartwig cross-coupling reaction, which paves the way towards using iron(II) clathrochelate as modular building blocks to make various functional polymers structures [6].

Scheme 3. Synthesis of porous metal organic Copolymers containing iron(II) clathrochelate units via palladium catalyzed Sonogashira cross-coupling reaction

The synthesis of metalorganic copolymers made from the palladium catalyzed Sonogashira cross-coupling reaction between various iron(II) clathrochelate building blocks with diethynyl- triptycene and fluorene derivatives CCP1-5 and from palladium catalyzed Sonogashira cross-coupling reaction using an iron(II) clathrochelate synthon end-capped with ethynyl groups with various brominated arylamine derivatives CLA1-4 were discovered. The resulted copolymers show very good BET surface area up to ~411 m2 g-1 and excellent iodine uptake with a maximum adsorption of 200 wt.%. The target copolymers also exhibit maximum adsorption capacity (qm) for Methylene Blue and Congo Red of 146.63 mg g-1 and 787.40 mg g-1, respectively. [7,8].

2. New Triptycene Derivatives

Scheme 4. Synthesis of new oligophenyl derivatives

New triptycene derivatives were prepared by microwave-assisted [4+2] Diels–Alder cycloaddition reactions in followed by palladium-catalyzed BuchwaldeHartwig Cross-Coupling reactions in very good overall yields. This successful tetra- and octa-fold substitution paves the way for the employment of these building blocks to prepare polymer networks for various applications and the star-shaped dendrimers revealed their violet and blue fluorescent properties, thus, promoting them as promising materials for emission applications. [9, 10].

  1. Gong, W.; Xie, Y.; Pham, T.D.; Shetty, S.; Son, F.A.; Idrees, K.B.; Chen, Z.; Xie, H.; Liu, Y.; Snurr, R.Q.; et al. Creating Optimal Pockets in a Clathrochelate-Based Metal–Organic Framework for Gas Adsorption and Separation: Experimental and Computational Studies. Journal of the American Chemical Society 2022, 144, 3737-3745.
  2. Noorullah Baig, Suchetha Shetty, Sameh S. Habib, Ali A. Husain, Saleh Al-Mousawi and Bassam Alameddine; Synthesis of Iron(II) Clathrochelate-Based Poly(vinylene sulfide) with Tetraphenylbenzene Bridging Units and their Selective Oxidation into their Corresponding Poly(vinylene sulfone) Copolymers: Promising Materials for Iodine Capture. polymers (MDPI).
  3. Chen, Z.; Idrees, K.B.; Shetty, S.; Xie, H.; Wasson, M.C.; Gong, W.; Zhang, X.; Alameddine, B.; Farha, O.K. Regulation of Catenation in Metal–Organic Frameworks with Tunable Clathrochelate-Based Building Blocks. Crystal Growth & Design 2021, 21, 6665-6670.
  4. N. Baig, S. Shetty, S. Al-Mousawi, F. Al-Sagheer and B. Alameddine, Influence of size and nature of the aryl diborate spacer on the intrinsic microporosity of Iron(II) clathrochelate polymers. Polymer, 2018, 151, 164-170.
  5. Shetty, S.; Baig, N.; Moustafa, M.S.; Al-Mousawi, S.; Alameddine, B. Synthesis of Metalorganic Copolymers Containing Various Contorted Units and Iron(II) Clathrochelates with Lateral Butyl Chains: Conspicuous Adsorbents of Lithium Ions and Methylene Blue. Polymer 2022, 14(16), 3394.
  6. S. Shetty, N. Baig, S. Al-Mousawi, F. Al-Sagheer, B. Alameddine. Synthesis of secondary arylamine copolymers with Iron(II) clathrochelate units and their functionalization into tertiary Polyarylamines via Buchwald-Hartwig cross-coupling reaction. Polymer 2019, 178, 121606.
  7. Shetty, S.; Baig, N.; Hassan, A.; Al-Mousawi, S.; Das, N.; Alameddine, B. Fluorinated Iron(ii) clathrochelate units in metalorganic based copolymers: improved porosity, iodine uptake, and dye adsorption properties. RSC Advances 2021, 11, 14986-14995.
  8. Shetty, S.; Baig, N.; Al-Mousawi, S.; Alameddine, B. Removal of anionic and cationic dyes using porous copolymer networks made from a Sonogashira cross-coupling reaction of diethynyl iron (II) clathrochelate with various arylamines. Journal of Applied Polymer Science 2022, n/a, e52966.
  9. B. Alameddine, N. Baig, S. Shetty, F. Al-Sagheer and S. Al-Mousawi, Microwave-Assisted [4+2] Diels–Alder Cycloaddition of 1,4-Diethynyl Triptycene with Various Cyclopentadienone Derivatives:Promising Building Blocks for Polymer Networks. Asian Journal of Organic Chemistry, 2018, 7, 378-382.
  10. B. Alameddine, S. Shetty, N. Baig and S. Al-Mousawi, Star-shaped tetra- and octa-arylamine triptycene-based dendrimers:modular building blocks for blue emission materials. Materials Today Chemistry 14 (2019) 100190

3. Cycloaddition reactions

Scheme 5: Synthesis of cyclobenzannulated (right) and cyclopentannulated (left) polymers

Five conjugated microporous polymers CBP1–5 were successfully synthesized through a copper-catalyzed [4 + 2] cyclobenzannulation reaction in excellent yields. The intrinsic surface areas, iodine uptake and organic dye adsorption were thoroughly investigated for all the polymers [N. Baig, 2021, RSC polymer chemistry].

A new class of conjugated organic polymers CPP1–3 were synthesized via a versatile palladium-catalyzed cyclopentannulation reaction. The target polymers were obtained in excellent yields and were found to be highly soluble in common organic solvents. Hence, CPP1–3 were characterized by GPC, NMR, FTIR, UV-vis absorption and emission spectroscopy. In addition, the target polymers were investigated for iodine uptake applications [N. Baig, 2020, RSC polymer chemistry].

4. Porous polymers

Figure 1: Synthesis of troger base containing porous polymers (left); Nitrogen adsorption and desorption isotherms (right) of TBP1-3 measured at 77 K

Figure 2: (A) Synthesis of contorted porous polymers and Selective dye removal capability of CP2 from a mixed solution of MB and MO (B) Synthesis of Polyphenylene networks containing triptycene units

New cross-linked copolymers bearing contorted aromatic units and polar nitrile groups were made in high yields from commercially available reagents via a simple polycondensation/Suzuki/Sonogashira cross-coupling reactions. The target copolymers were obtained in excellent yields and tested for N2 adsorption, selective dyes adsorption and iodine uptake capacity [S. Shetty, 2021, Polymer; N. Baig, 2022, polymer]. The triptycene-based three-dimensional networks (B) were explored their uptake towards various gases such as N2, H2, CO2, and CH4 are described [S. Shetty, 2020, Microporous and Mesoporous Materials].

Figure 3: Synthesis of sulfone copolymers made from a metal-free thiol-yne click reaction followed by oxidationcontorted (left); Methylene blue MEB dye removal capability of TCP6 from aqueous solution (right)

Copolymers bearing triptycene and Trӧger's base units intercalated with various thioether groups were synthesized using a catalyst-free thiol-yne click reaction. The thioether groups were selectively oxidized into their respective sulfone derivatives under mild oxidation reaction conditions affording the postmodified copolymers. Investigation of organic dye uptake from water by Trӧger's base containing copolymers proved their efficiency as selective adsorbents removing up to 100% of the cationic dye methylene blue (MEB) when compared to anionic dyes, such as Congo red (CR), methyl orange (MO) and methyl blue (MB) [N. Baig, 2021, RSC Advances, B. Alameddine, 2018, Polymer].

Figure 3: Synthesis of two and three-dimensional copolymer derivatives containing triptycene units (left); Normalized UV–vis absorption and emission spectra of polymers 3c, and 4c in THF (right)

A series of two and three-dimensional polymer derivatives containing triptycene comonomers were synthesized from 1,4-diethynyl triptycene with various di-, tri-, and tetra-brominated aromatic building blocks through the mild Sonogashira cross-coupling reaction conditions. The abovementioned alkyne-containing copolymers were subsequently oxidized into their respective 1,2-diketone derivatives. Two-dimensional polymer derivatives act as blue emitters [N. Baig, 2019, Reactive and Functional Polymers; B. Alameddine, 2018, Journal of Polymer Science, PART A: Polymer Chemistry].

5. Donor-acceptor copolymers as transistors

Figure 3: Synthesis of Donor-acceptor copolymers and Output characteristic of an annealed hole-only PNP1 OFET

Herein, we describe the synthesis, characterization, thermal, and, optical properties of six novel Donor-acceptor (D-A) conjugated polymers, which contain either phenanthrene-9,10-dione or dibenzo[f,h]quinoxaline as the acceptor unit with various donor comonomers. The charge transport properties of functionalized copolymers were explored revealing a hole mobility in the range of 10–6- 10–7 cm2 V–1s–1 [N. Baig, 2018, Materials Today Chemistry; B. Alameddine, 2019, Polymer; N. Baig, 2020, New Journal of Chemistry].

  1. Noorullah Baig, S. Shetty, S. Al-Mousawi, and B. Alameddine,“Conjugated microporous polymers using a copper-catalyzed [4 + 2] cyclobenzannulation reaction: promising materials for iodine and dye adsorption” RSC polymer chemistry, 2021,12, 2282.
  2. Noorullah Baig, S. Shetty, S. Al-Mousawi, and B. Alameddine, “Synthesis of conjugated polymers via cyclopentannulation reaction: promising materials for iodine adsorption” RSC polymer chemistry, 2020, 11, 3066.
  3. Suchetha Shetty, N. Baig, M. S. Moustafa, S. Al-Mousawi, and B. Alameddine, Sizable iodine uptake of porous copolymer networks bearing Tröger's base units. Polymer, 2021, 229, 123996.
  4. Noorullah Baig, S. Shetty, S.S. Pasha, S.K. Pramanik, and B. Alameddine, “Copolymer networks with contorted units and highly polar groups for ultra-fast selective cationic dye adsorption and iodine uptake” Polymer, 2022, 239, 124467.
  5. Suchetha Shetty, N. Baig, A. Hassan, S. Al-Mousawi, N. Das, and B. Alameddine, “Polyphenylene Networks Containing Triptycene Units: Promising Porous Materials for CO2, CH4, and H2 Adsorption” Microporous and Mesoporous Materials, 2020, 303, 110256.
  6. Noorullah Baig, S. Shetty, M. S. Moustafa, S. Al-Mousawi, and B. Alameddine, “Selective removal of toxic organic dyes using Trӧger base-containing sulfone copolymers made from a metal-free thiol-yne click reaction followed by oxidation” RSC Advances, 2021, 11, 21170.
  7. Bassam Alameddine, N. Baig, S. Shetty, S. Al-Mousawi, F. Al-Sagheer, and, “Triptycene-Containing Poly(vinylene sulfone) Derivatives From a Metal-Free Thiol-Yne Click Polymerization Followed by a Mild Oxidation Reaction” Polymer, 2018, 154, 233-240.
  8. Noorullah Baig, S. Shetty, S. Al-Mousawi, F. Al-Sagheer, B. Alameddine, “Synthesis of triptycene-derived covalent organic polymer networks and their subsequent in-situ functionalization with 1,2-dicarbonyl substituents” Reactive and Functional Polymers, 2019, 139, 153-161.
  9. Bassam Alameddine, Noorullah Baig, S. Shetty, S. Al-Mousawi, F. Al-Sagheer, “Tuning the optical properties of ethynylene triptycene-based copolymers via oxidation of their alkyne groups into α-diketones” Journal of Polymer Science, PART A: Polymer Chemistry 2018, 56, 8, 931-937.
  10. Noorullah Baig, S. Shetty, S. Al-Mousawi, F. Al-Sagheer, B. Alameddine, “Synthesis, characterization, thermal, and optical properties of conjugated copolymers derived from phenanthrene-9,10-dione- and dibenzo[f,h]quinoxaline” Materials Today Chemistry, 2018, 10, 213-220.
  11. Bassam Alameddine, Noorullah Baig, S. Shetty, S. Al-Mousawi, “Conjugated copolymers bearing 2,7-di(thiophen-2-yl)phenanthrene-9,10-dione units and alteration of their emission via functionalization of the ortho-dicarbonyl groups into quinoxaline and phenazine derivatives” Polymer, 2019, 178, 121589.
  12. Noorullah Baig, S. Shetty, S. Fall, S. Al-Mousawi, T. Heiser, and B. Alameddine, “Conjugated copolymers bearing 2,7-dithienylphenanthrene-9,10-dialkoxy units: highly soluble and stable deep-blue emissive materials” New Journal of Chemistry, 2020, 44, 9557-9564.