Large Coercivity and High Remanent Magnetization Organic-Based Magnets

Abstract

Coercivity is an important history-and defect-dependent property of magnets [1] and needs to be large for many applications, e.g., magnetic storage, or small in value for other applications, e.g., AC inductors or magnetic shielding.[2]Some metallurgically prepared classical magnets, with spins residing in metal d-or f-orbitals, exhibit high coercivity, which enables their use in a myriad of applications, including the magnetic storage of information. [2] With the advent of magnets composed of spin-bearing organic components, [3] new classes of magnets with combinations of properties not previously observed are emerging.[4] Organicbased magnets were unfathomable a little more than decade ago, but magnetic ordering temperatures, T c , exceeding room temperature have been achieved. [5,6] [10a,11a,b,12,13] Magnetic ordering occurs below 10.0 K, as determined from the maximum in the 10 Hz w¢(T) data. The frequency dependence of the maxima in the in-phase component of the AC susceptibility, w¢(T), data suggests (cluster) spin glass behavior [11b±d] as noted for 3 and desolvated 3.[11a] The presence of an outof-phase component of the AC susceptibility, w²(T), with a maximum at 7.6 K (10 Hz) supports the assignment of a transition to a canted antiferromagnet below T c . [14] Independent of temperature, the applied magnetic field dependence on the magnetization, M(H), reaches a value of 16 500 emu Oe/mol at 50 kOe and is still increasing (Fig. 2). These values are in good agreement with the expectation of 16 755 emu Oe/mol for antiferromagnetic coupling of

Microwave-assisted synthesis and reverse saturable absorption of phthalocyanines and porphyrins

“…Preparation of tetrakis (2,9,16,23-cumylphenoxy) copper phthalocyanines (CuPc(b-CP) 4 ) (Scheme 1) and tetrakis (1,8,15,22- (2,9,16,23-tert-butyl) copper phthalocyanines (CuPc(b-t-butyl) 4 …”

“…Phthalocyanines and porphyrins have attracted attention for many decades because of their comprehensive applications such as molecular thermometers [1], light-emitting diodes [2,3], magnets [4], solar cells [5,6], and photodynamic therapy [7]. In recent years, porphyrin and phthalocyanines molecules have been observed to exhibit reverse saturable absorption (RSA) [8,9] in solutions due to their planar p-conjugated electron systems.…”

Synthesis, crystal structure and magnetic property of an unusual formate-bridged heterometallic binuclear CrIIIMnIII porphyrin complex

“…Recently, several groups are also interested in design and assembly of molecule-based magnetic materials derived from manganese(III) porphyrin building blocks for some well known excellent characteristics of Mn(III) ions in magnetism. In fact, some examples of one-dimensional molecular magnetic materials exhibiting interesting single-chain magnet (SCM) or ferrimagnet behavior have been obtained successfully based on manganese(III) porphyrin building blocks and TCNE ÅÀ or phenylphosphinic acid as magnetic exchanging bridges [11][12][13].…”

“…Recently, several groups are also interested in design and assembly of molecule-based magnetic materials derived from manganese(III) porphyrin building blocks for some well known excellent characteristics of Mn(III) ions in magnetism. In fact, some examples of one-dimensional molecular magnetic materials exhibiting interesting single-chain magnet (SCM) or ferrimagnet behavior have been obtained successfully based on manganese(III) porphyrin building blocks and TCNE ÅÀ or phenylphosphinic acid as magnetic exchanging bridges [11][12][13].In our continuous efforts to assemble new cyanide-bridged magnetic complexes based on manganese(III) compound containing salen-typed Schiff-base ligands [14], we hope to expand the system to cyanide-bridged manganese(III) porphyrin complex. With an aim to synthesize low-dimensional cyanide-bridged heterobimetallic Cr III -Mn III complex, we carried out the reaction of dicyaninechromium building block K[Cr(bpb)(CN) 2 ] [15] containing two trans cyanide groups with [Mn(TClPP)(H 2 O) 2 ]ClO 4 possessing two trans replaceable sites being occupied by two water molecules.…”

Organic Magnets—A History

“…6). [39] ESSAY J. S. Miller/Organic MagnetsÐA History The apparent contradiction between the 3D magnetic behavior and 1D structure for Mn II (L F ) 2 NIT( i Pr) led to the appreciation of the importance of dipolar interactions in 1989 by Gatteschi, Rey, and co-workers. [35] Dipolar coupling leading to magnetic ordering has be invoked for the [Mn III (porphyrin)] + [TCNE] ç ± family of magnets [40] as well as some layered magnets.…”