Double-Stranded Binuclear Helicates and Helicity Modulation

All of the reported self-assembled complexes of <i>cis</i>-Pd₂L′₂L₂ formulation, where L′ stands for a chelating bidentate ligand and L for a nonchelating bidentate ligand, are “non-helical”. We disclose here the debut of the long awaited “helicate” type architecture of the <i>cis-</i>Pd₂L′₂L₂ formulation. In the present work, the term L′ stands for tetramethylethylenediamine (<i>tmeda</i>) and L stands for a (1<i>H</i>-imidazolyl)­methyl-appended bidentate nonchelating ligand having a rigid spacer. The torsion angle between the two coordination PdN₄ planes of a given “helicate” is considered here as its magnitude of helicity. Length of spacer unit (i.e., 1,4-benzene, 4,4′-biphenyl and 4,4′-<i>p</i>-terphenyl) crafted in the backbone of L is found to impart such conformation to the bound ligand moieties that the magnitude of helicity is modulated

Consequence of Presence and Absence of π‑Clouds at Strategic Locations of Designed Binuclear Pd(II) Complexes on Packing: Self-Assembly of Self-Assembly by Intermolecular Locking and Packing

Self-assembled binuclear coordination cages of general formula [Pd₂(N–N)₂(<b>L</b>)₂]­(X)₄, <b>1a/b</b>–<b>4a/b</b> are prepared by the combination of <i>N</i>,<i>N</i>′-bis­(<i>m</i>-pyridyl)­urea, <b>L</b>, with a variety of <i>cis</i>-protected palladium­(II) components, Pd­(N–N)­(X)₂. The <i>cis</i>-protecting units “N–N” employed for the synthesis of <b>1</b>–<b>4</b> are ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen), respectively. The term “X” stands for nitrate and perchlorate for <b>a</b> and <b>b</b>, respectively. The assemblies are characterized by NMR and electrospray ionization mass spectrometry (ESI-MS) techniques, and in some cases (i.e., <b>1a</b>,<b> 2b</b>,<b> 3b</b>,<b> 4a</b>, and <b>4b</b>) the structures are confirmed by single crystal X-ray diffraction. The conformations of bound <b>L</b> in the crystal structures of all the Pd­(II) complexes are found to be <i>syn-syn</i>. The influence of the presence and absence of π cloud at the <i>cis-</i>protecting units on the crystal packing has been studied in detail. In the packing of [Pd₂(phen)₂<b>L</b>₂]­(NO₃)₄, <b>4a</b>, one unit of [Pd₂(phen)₂<b>L</b>₂]⁴⁺ is associated with two other units by π–π stacking interactions thus giving a one-dimensional growth as envisioned on the basis of a design principle. In the case of [Pd₂(en)₂(<b>L)</b>₂]­(NO₃)₄, <b>1a</b>, and [Pd₂(tmeda)₂(<b>L</b>)₂]­(ClO₄)₄, <b>2b</b>, such packing is not observed due to the absence of π-cloud at the strategic locations, instead notable H-bonding interactions are seen. However, [Pd₂(bpy)₂(<b>L</b>)₂]­(ClO₄)₄, <b>3b</b>, displays a π–π interactions using only two units of [Pd₂(bpy)₂(<b>L</b>)₂]⁴⁺(ClO₄)⁻

Consequence of Presence and Absence of π‑Clouds at Strategic Locations of Designed Binuclear Pd(II) Complexes on Packing: Self-Assembly of Self-Assembly by Intermolecular Locking and Packing

Self-assembled binuclear coordination cages of general formula [Pd₂(N–N)₂(<b>L</b>)₂]­(X)₄, <b>1a/b</b>–<b>4a/b</b> are prepared by the combination of <i>N</i>,<i>N</i>′-bis­(<i>m</i>-pyridyl)­urea, <b>L</b>, with a variety of <i>cis</i>-protected palladium­(II) components, Pd­(N–N)­(X)₂. The <i>cis</i>-protecting units “N–N” employed for the synthesis of <b>1</b>–<b>4</b> are ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen), respectively. The term “X” stands for nitrate and perchlorate for <b>a</b> and <b>b</b>, respectively. The assemblies are characterized by NMR and electrospray ionization mass spectrometry (ESI-MS) techniques, and in some cases (i.e., <b>1a</b>,<b> 2b</b>,<b> 3b</b>,<b> 4a</b>, and <b>4b</b>) the structures are confirmed by single crystal X-ray diffraction. The conformations of bound <b>L</b> in the crystal structures of all the Pd­(II) complexes are found to be <i>syn-syn</i>. The influence of the presence and absence of π cloud at the <i>cis-</i>protecting units on the crystal packing has been studied in detail. In the packing of [Pd₂(phen)₂<b>L</b>₂]­(NO₃)₄, <b>4a</b>, one unit of [Pd₂(phen)₂<b>L</b>₂]⁴⁺ is associated with two other units by π–π stacking interactions thus giving a one-dimensional growth as envisioned on the basis of a design principle. In the case of [Pd₂(en)₂(<b>L)</b>₂]­(NO₃)₄, <b>1a</b>, and [Pd₂(tmeda)₂(<b>L</b>)₂]­(ClO₄)₄, <b>2b</b>, such packing is not observed due to the absence of π-cloud at the strategic locations, instead notable H-bonding interactions are seen. However, [Pd₂(bpy)₂(<b>L</b>)₂]­(ClO₄)₄, <b>3b</b>, displays a π–π interactions using only two units of [Pd₂(bpy)₂(<b>L</b>)₂]⁴⁺(ClO₄)⁻

Consequence of Presence and Absence of π‑Clouds at Strategic Locations of Designed Binuclear Pd(II) Complexes on Packing: Self-Assembly of Self-Assembly by Intermolecular Locking and Packing

Self-assembled binuclear coordination cages of general formula [Pd₂(N–N)₂(<b>L</b>)₂]­(X)₄, <b>1a/b</b>–<b>4a/b</b> are prepared by the combination of <i>N</i>,<i>N</i>′-bis­(<i>m</i>-pyridyl)­urea, <b>L</b>, with a variety of <i>cis</i>-protected palladium­(II) components, Pd­(N–N)­(X)₂. The <i>cis</i>-protecting units “N–N” employed for the synthesis of <b>1</b>–<b>4</b> are ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen), respectively. The term “X” stands for nitrate and perchlorate for <b>a</b> and <b>b</b>, respectively. The assemblies are characterized by NMR and electrospray ionization mass spectrometry (ESI-MS) techniques, and in some cases (i.e., <b>1a</b>,<b> 2b</b>,<b> 3b</b>,<b> 4a</b>, and <b>4b</b>) the structures are confirmed by single crystal X-ray diffraction. The conformations of bound <b>L</b> in the crystal structures of all the Pd­(II) complexes are found to be <i>syn-syn</i>. The influence of the presence and absence of π cloud at the <i>cis-</i>protecting units on the crystal packing has been studied in detail. In the packing of [Pd₂(phen)₂<b>L</b>₂]­(NO₃)₄, <b>4a</b>, one unit of [Pd₂(phen)₂<b>L</b>₂]⁴⁺ is associated with two other units by π–π stacking interactions thus giving a one-dimensional growth as envisioned on the basis of a design principle. In the case of [Pd₂(en)₂(<b>L)</b>₂]­(NO₃)₄, <b>1a</b>, and [Pd₂(tmeda)₂(<b>L</b>)₂]­(ClO₄)₄, <b>2b</b>, such packing is not observed due to the absence of π-cloud at the strategic locations, instead notable H-bonding interactions are seen. However, [Pd₂(bpy)₂(<b>L</b>)₂]­(ClO₄)₄, <b>3b</b>, displays a π–π interactions using only two units of [Pd₂(bpy)₂(<b>L</b>)₂]⁴⁺(ClO₄)⁻

Consequence of Presence and Absence of π‑Clouds at Strategic Locations of Designed Binuclear Pd(II) Complexes on Packing: Self-Assembly of Self-Assembly by Intermolecular Locking and Packing

Self-assembled binuclear coordination cages of general formula [Pd₂(N–N)₂(<b>L</b>)₂]­(X)₄, <b>1a/b</b>–<b>4a/b</b> are prepared by the combination of <i>N</i>,<i>N</i>′-bis­(<i>m</i>-pyridyl)­urea, <b>L</b>, with a variety of <i>cis</i>-protected palladium­(II) components, Pd­(N–N)­(X)₂. The <i>cis</i>-protecting units “N–N” employed for the synthesis of <b>1</b>–<b>4</b> are ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen), respectively. The term “X” stands for nitrate and perchlorate for <b>a</b> and <b>b</b>, respectively. The assemblies are characterized by NMR and electrospray ionization mass spectrometry (ESI-MS) techniques, and in some cases (i.e., <b>1a</b>,<b> 2b</b>,<b> 3b</b>,<b> 4a</b>, and <b>4b</b>) the structures are confirmed by single crystal X-ray diffraction. The conformations of bound <b>L</b> in the crystal structures of all the Pd­(II) complexes are found to be <i>syn-syn</i>. The influence of the presence and absence of π cloud at the <i>cis-</i>protecting units on the crystal packing has been studied in detail. In the packing of [Pd₂(phen)₂<b>L</b>₂]­(NO₃)₄, <b>4a</b>, one unit of [Pd₂(phen)₂<b>L</b>₂]⁴⁺ is associated with two other units by π–π stacking interactions thus giving a one-dimensional growth as envisioned on the basis of a design principle. In the case of [Pd₂(en)₂(<b>L)</b>₂]­(NO₃)₄, <b>1a</b>, and [Pd₂(tmeda)₂(<b>L</b>)₂]­(ClO₄)₄, <b>2b</b>, such packing is not observed due to the absence of π-cloud at the strategic locations, instead notable H-bonding interactions are seen. However, [Pd₂(bpy)₂(<b>L</b>)₂]­(ClO₄)₄, <b>3b</b>, displays a π–π interactions using only two units of [Pd₂(bpy)₂(<b>L</b>)₂]⁴⁺(ClO₄)⁻

Consequence of Presence and Absence of π‑Clouds at Strategic Locations of Designed Binuclear Pd(II) Complexes on Packing: Self-Assembly of Self-Assembly by Intermolecular Locking and Packing

Self-assembled binuclear coordination cages of general formula [Pd₂(N–N)₂(<b>L</b>)₂]­(X)₄, <b>1a/b</b>–<b>4a/b</b> are prepared by the combination of <i>N</i>,<i>N</i>′-bis­(<i>m</i>-pyridyl)­urea, <b>L</b>, with a variety of <i>cis</i>-protected palladium­(II) components, Pd­(N–N)­(X)₂. The <i>cis</i>-protecting units “N–N” employed for the synthesis of <b>1</b>–<b>4</b> are ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen), respectively. The term “X” stands for nitrate and perchlorate for <b>a</b> and <b>b</b>, respectively. The assemblies are characterized by NMR and electrospray ionization mass spectrometry (ESI-MS) techniques, and in some cases (i.e., <b>1a</b>,<b> 2b</b>,<b> 3b</b>,<b> 4a</b>, and <b>4b</b>) the structures are confirmed by single crystal X-ray diffraction. The conformations of bound <b>L</b> in the crystal structures of all the Pd­(II) complexes are found to be <i>syn-syn</i>. The influence of the presence and absence of π cloud at the <i>cis-</i>protecting units on the crystal packing has been studied in detail. In the packing of [Pd₂(phen)₂<b>L</b>₂]­(NO₃)₄, <b>4a</b>, one unit of [Pd₂(phen)₂<b>L</b>₂]⁴⁺ is associated with two other units by π–π stacking interactions thus giving a one-dimensional growth as envisioned on the basis of a design principle. In the case of [Pd₂(en)₂(<b>L)</b>₂]­(NO₃)₄, <b>1a</b>, and [Pd₂(tmeda)₂(<b>L</b>)₂]­(ClO₄)₄, <b>2b</b>, such packing is not observed due to the absence of π-cloud at the strategic locations, instead notable H-bonding interactions are seen. However, [Pd₂(bpy)₂(<b>L</b>)₂]­(ClO₄)₄, <b>3b</b>, displays a π–π interactions using only two units of [Pd₂(bpy)₂(<b>L</b>)₂]⁴⁺(ClO₄)⁻

Consequence of Presence and Absence of π‑Clouds at Strategic Locations of Designed Binuclear Pd(II) Complexes on Packing: Self-Assembly of Self-Assembly by Intermolecular Locking and Packing

Self-assembled binuclear coordination cages of general formula [Pd₂(N–N)₂(<b>L</b>)₂]­(X)₄, <b>1a/b</b>–<b>4a/b</b> are prepared by the combination of <i>N</i>,<i>N</i>′-bis­(<i>m</i>-pyridyl)­urea, <b>L</b>, with a variety of <i>cis</i>-protected palladium­(II) components, Pd­(N–N)­(X)₂. The <i>cis</i>-protecting units “N–N” employed for the synthesis of <b>1</b>–<b>4</b> are ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen), respectively. The term “X” stands for nitrate and perchlorate for <b>a</b> and <b>b</b>, respectively. The assemblies are characterized by NMR and electrospray ionization mass spectrometry (ESI-MS) techniques, and in some cases (i.e., <b>1a</b>,<b> 2b</b>,<b> 3b</b>,<b> 4a</b>, and <b>4b</b>) the structures are confirmed by single crystal X-ray diffraction. The conformations of bound <b>L</b> in the crystal structures of all the Pd­(II) complexes are found to be <i>syn-syn</i>. The influence of the presence and absence of π cloud at the <i>cis-</i>protecting units on the crystal packing has been studied in detail. In the packing of [Pd₂(phen)₂<b>L</b>₂]­(NO₃)₄, <b>4a</b>, one unit of [Pd₂(phen)₂<b>L</b>₂]⁴⁺ is associated with two other units by π–π stacking interactions thus giving a one-dimensional growth as envisioned on the basis of a design principle. In the case of [Pd₂(en)₂(<b>L)</b>₂]­(NO₃)₄, <b>1a</b>, and [Pd₂(tmeda)₂(<b>L</b>)₂]­(ClO₄)₄, <b>2b</b>, such packing is not observed due to the absence of π-cloud at the strategic locations, instead notable H-bonding interactions are seen. However, [Pd₂(bpy)₂(<b>L</b>)₂]­(ClO₄)₄, <b>3b</b>, displays a π–π interactions using only two units of [Pd₂(bpy)₂(<b>L</b>)₂]⁴⁺(ClO₄)⁻

Consequence of Presence and Absence of π‑Clouds at Strategic Locations of Designed Binuclear Pd(II) Complexes on Packing: Self-Assembly of Self-Assembly by Intermolecular Locking and Packing

Self-assembled binuclear coordination cages of general formula [Pd₂(N–N)₂(<b>L</b>)₂]­(X)₄, <b>1a/b</b>–<b>4a/b</b> are prepared by the combination of <i>N</i>,<i>N</i>′-bis­(<i>m</i>-pyridyl)­urea, <b>L</b>, with a variety of <i>cis</i>-protected palladium­(II) components, Pd­(N–N)­(X)₂. The <i>cis</i>-protecting units “N–N” employed for the synthesis of <b>1</b>–<b>4</b> are ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen), respectively. The term “X” stands for nitrate and perchlorate for <b>a</b> and <b>b</b>, respectively. The assemblies are characterized by NMR and electrospray ionization mass spectrometry (ESI-MS) techniques, and in some cases (i.e., <b>1a</b>,<b> 2b</b>,<b> 3b</b>,<b> 4a</b>, and <b>4b</b>) the structures are confirmed by single crystal X-ray diffraction. The conformations of bound <b>L</b> in the crystal structures of all the Pd­(II) complexes are found to be <i>syn-syn</i>. The influence of the presence and absence of π cloud at the <i>cis-</i>protecting units on the crystal packing has been studied in detail. In the packing of [Pd₂(phen)₂<b>L</b>₂]­(NO₃)₄, <b>4a</b>, one unit of [Pd₂(phen)₂<b>L</b>₂]⁴⁺ is associated with two other units by π–π stacking interactions thus giving a one-dimensional growth as envisioned on the basis of a design principle. In the case of [Pd₂(en)₂(<b>L)</b>₂]­(NO₃)₄, <b>1a</b>, and [Pd₂(tmeda)₂(<b>L</b>)₂]­(ClO₄)₄, <b>2b</b>, such packing is not observed due to the absence of π-cloud at the strategic locations, instead notable H-bonding interactions are seen. However, [Pd₂(bpy)₂(<b>L</b>)₂]­(ClO₄)₄, <b>3b</b>, displays a π–π interactions using only two units of [Pd₂(bpy)₂(<b>L</b>)₂]⁴⁺(ClO₄)⁻