Related Experiment Video
Updated: Jul 5, 2026
12:34
Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence
Published on: June 24, 2016
Spin-crossover dendrimers: generation number-dependent cooperativity for thermal spin transition
Tsuyohiko Fujigaya1, Dong-Lin Jiang, Takuzo Aida
1Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Journal of the American Chemical Society
|April 14, 2005
Summary
Dendritic coordination polymers with triazole units exhibit thermal spin transitions. Increasing dendron generation number lowers polymerization and transition temperature, but spin transition abruptness varies, with G1trzFe showing the sharpest change.
Area of Science:
- Coordination polymer chemistry
- Materials science
- Supramolecular chemistry
Background:
- Poly(benzyl ether) dendrons with focal triazole units were synthesized.
- Iron(II) complexes with these dendrons form dendritic coordination polymers.
- These polymers exhibit thermal spin transitions.
Purpose of the Study:
- To investigate the effect of dendron generation number on the spin transition properties of dendritic coordination polymers.
- To characterize the structure and thermal behavior of these novel materials.
Main Methods:
- Synthesis of poly(benzyl ether) dendrons with triazole units (Gntrz, n=0-2).
- Reaction with (MeSO3)2Fe to form dendritic coordination polymers ([Fe(Gntrz)3](MeSO3)2.2H2O).
- Analysis of thermal spin transition using calorimetry and X-ray diffraction.
Main Results:
- Spin-crossover temperature (Tc) decreased with increasing dendron generation (n=0: 335 K, n=1: 315 K, n=2: 300 K).
- Average degree of polymerization decreased with increasing generation (n=0: 20, n=1: 10, n=2: 3).
- Spin transition abruptness varied: G1trzFe showed a narrow width (10 K), while G0trzFe (30 K) and G2trzFe (50 K) had broader transitions.
- X-ray diffraction and calorimetry revealed a discotic columnar core-shell assembly.
Conclusions:
- The generation number of dendritic units influences the spin transition temperature and degree of polymerization in coordination polymers.
- The abruptness of the spin transition is not solely dependent on the generation number.
- Dendritic coordination polymers form ordered supramolecular structures with potential applications in materials science.
Related Concept Videos
01:06Parallel-axis Theorem
The parallel-axis theorem provides a convenient and quick method of finding the moment of inertia of an object about an axis parallel to the axis passing through its center of mass. Consider a thin rod as an example. There is a striking similarity between the process of finding the moment of inertia of a thin rod about an axis through its middle, where the center of mass lies, and about an axis through its end using the conventional method. In the conventional method, the concept of linear mass...
01:13Angle of Twist: Problem Solving
An electric motor applies a torque of 700 N·m to an aluminum shaft, triggering a stable rotation. Two pulleys, B and C, are subjected to torques of 300 N·m and 400 N·m, respectively. The modulus of rigidity is provided as 25 GPa. With the knowledge of the length and diameter of each segment, the twist angle between the two pulleys can be computed. First, a section cut is made between pulleys B and C, and the cut cross-section is analyzed using a free-body diagram. Given that the torque exerted...
01:12Transformation of Plane Strain
When analyzing elongated structures like bars subjected to uniformly distributed loads, it is essential to understand the transformation of plane strain when coordinate axes are rotated. This transformation helps to assess how material deformation characteristics vary with orientation, which is crucial in materials science and structural engineering.
Under plane strain conditions, typical for members where one dimension significantly exceeds the others, deformations and resultant strains are...
Under plane strain conditions, typical for members where one dimension significantly exceeds the others, deformations and resultant strains are...
01:20Torsion in Vector Calculus
A toy train ascending a winding track that curves and tilts offers an intuitive view of torsion, a key geometric concept in the study of space curves. While curvature measures how sharply a path bends, torsion captures how the path twists out of the plane of bending. This twisting behavior is crucial in understanding three-dimensional motion and is precisely described using the Frenet–Serret framework.At each point along a space curve, the Frenet–Serret frame consists of three orthogonal unit...
01:27Green’s Theorem
Green’s Theorem establishes a relationship between a line integral around a closed plane curve and a double integral over the region enclosed by that curve. It applies to a vector field F(x, y) = 〈P(x, y), Q(x, y)〉, where P and Q have continuous first partial derivatives on an open set containing the region.Let C be a positively oriented, simple, closed, piecewise smooth curve, and let R be the plane region bounded by C. Green’s Theorem states that\begin{equation*}\oint_C P\,dx+Q\,dy =\iint_R...
01:26Vector Forms of Green’s Theorem
The study of fluid motion often involves understanding how local rotational behavior relates to global circulation. In the context of a pond with pollutants, direct measurement of water movement along an irregular shoreline can be impractical. Green’s Theorem in vector form provides an alternative by relating the circulation around a closed boundary to properties of the flow within the enclosed region.Measurements of water velocity at different points define a continuous vector field that...